Bump Marten from 9.39.1 to 9.47.0

[dependabot]

Updated Marten from 9.39.1 to 9.47.0.

Release notes

Sourced from Marten's releases.

9.47.0

The FetchForWriting / FetchLatest consistency release, plus a bounded async-daemon shutdown.

Read the behaviour changes before upgrading. Two of them can change how your projections and
subscriptions behave on every deployment, and two more refuse a batch shape that used to be accepted.

⚠️ Behaviour changes

Subscription and projection drains are now bounded by StopAndDrainTimeout ([#​5610])

Via JasperFx 2.81.0 (jasperfx#​953 and jasperfx#​983). When a shard stops — host shutdown, or reassignment
to another node — the page in flight finishes, pages still queued are skipped and resumed by the next
owner from committed progression, and a page still running at Projections.StopAndDrainTimeout
(default 5 seconds) is cancelled with its transaction rolled back.

This fixes a real failure: a node that loses a shard's lock no longer keeps applying its backlog
alongside the new owner, an overlap that could end in ProgressionProgressOutOfOrderException and a
Stopped shard. Graceful shutdown is also bounded now, rather than waiting out the whole backlog and
potentially overrunning a Kubernetes termination grace period.

If your projection or subscription pages take longer than 5 seconds, raise the timeout:

opts.Projections.StopAndDrainTimeout = 30.Seconds();

Otherwise those pages are cancelled and re-processed on every shutdown and rebalance. Delivery was
always at-least-once, so no guarantee changed, but duplicates become much more likely — and side effects
performed outside the Marten session (HTTP calls, sends that bypass the transactional outbox) are not
rolled back with the page. Note this applies to async projections as well as subscriptions; the upstream
note covers only subscriptions and is out of date.

A batched FetchLatest or expected-version FetchForWriting must be first in its batch ([#​5604])

For an aggregate projected with ProjectionLifecycle.Async only. Both now bracket their reads in
begin transaction isolation level repeatable read read only … end so those reads share one snapshot,
and PostgreSQL accepts that only as a transaction's first statement. So:

• batch.Events.FetchLatest<T>(id) and batch.Events.FetchForWriting<T>(id, version) have to be the
  first operation in their batch, and
• neither can share a batch with a FetchForExclusiveWriting.

Both are refused at the enlisting call, naming the call to move, rather than surfacing later as a bare
25001. Inline and Live aggregates are unaffected, and inside a caller-owned transaction no bracket is
emitted so neither rule applies. If you batch a FetchLatest behind a Load, move it to the front.

New SnapshotRaceException from a batched exclusive fetch ([#​5613])

A batched FetchForExclusiveWriting on an Async aggregate now throws Marten.Exceptions.SnapshotRaceException
in the rare case where the daemon commits a snapshot between that batch's two reads. Retry the batch, or
fetch outside a batch — outside a batch Marten retries for you and you will never see it.
... (truncated)

9.46.0

Mostly a resiliency and Native AOT release. Five behaviour changes — the retry ones are the most likely to be noticed, because Marten now surfaces failures it used to absorb.

Behaviour changes

A command timeout is no longer retried on reads (#​5566, #​5580). An attempt that timed out has already spent the whole CommandTimeout, so retrying it three times held the caller for four timeouts instead of one. This covers both shapes: Npgsql's client-side CommandTimeout, and a server-side statement_timeout, which arrives as 57014 query_canceled with no TimeoutException anywhere in the exception. Connection-pool exhaustion arrives in the same shape and so is no longer retried either — a deliberate trade, documented in the resiliency guide along with what to do instead.

Sticky, ambient and external session lifetimes now fail loudly (#​5582, #​5598), via the new SessionTransactionUnusableException. Two things used to go wrong silently. A broken connection reported ConnectionState.Closed, so Marten reopened it — onto a different backend — and handed the command the stale transaction, which Npgsql accepts; a Serializable session then quietly answered from a newer snapshot. And a command timeout inside a transaction aborted it, after which every later call returned a bare 25P02 naming neither the timeout nor the way out. For caller-owned transactions Marten records the cause and reports it but rolls nothing back — the scope is still yours.

The async serializable session builders now produce a serializable session (#​5594). OpenSerializableSessionAsync(new SessionOptions()) previously returned a session that was neither serializable nor auto-closing: it held one connection open for its lifetime with no transaction. These two methods now pin IsolationLevel to Serializable and begin the transaction eagerly. A non-Serializable level passed to them is overridden rather than silently honoured.

The async daemon spends one retry budget instead of two (#​5593). ResilientEventLoader and the QuerySession inside it were both given the same pipeline, so a handled failure ran up to sixteen times.

A retried write no longer accumulates exceptions across attempts (#​5591). The exception list was shared, and ExecuteBatchPagesAsync branches on its count — so one operation failing twice turned a rethrow into an AggregateException, making the caller's exception type depend on how many retries happened.

Native AOT

Strong-typed document ids now work (#​5589, #​5579), with one registration per document type:

opts.Schema.For<Invoice>();
opts.RegisterValueTypeId<Invoice, InvoiceId, Guid>();

Previously a single strong-typed id anywhere in the store killed the application while the first document's mapping was built. The identity path closes a chain of generics over your id type, and a native image has no instantiation for them unless something roots it; naming all three types is what roots them. Under a JIT the call does nothing — unregistered types still take the reflective path. Not yet covered: F# single-case discriminated-union ids, and .IsOneOf over a strong-typed id. The intent is for Marten.SourceGenerator to emit these registrations so the call becomes unnecessary.

Also AOT: a decimal comparison in a LINQ filter is documented with a tested workaround (#​5597) — it is the BCL expression-tree factory rather than Marten, but it only shows up from a native binary. Marten's AOT runtime gate now covers strong-typed ids and decimals, so these stay pinned.

Fixes

• PrefixSearch quotes each word as a tsquery lexeme (#​5571, #​5568), so a search box containing &, |, !, (, : or a tab no longer produces 42601: syntax error in tsquery. Not an injection — the term was already a parameter — but the documented contract says each word is treated as a prefix, and raw input has to be escaped to honour that.
• A quick append nulls every DCB tag slot, not just the tagged ones (#​5570).
• AdvisoryLock shutdown release is bounded, and the vendored copy moves back to Weasel (#​5572, #​5576).
• Three catch-and-Console.WriteLine-and-rethrow blocks removed (#​5584) — they bypassed IMartenSessionLogger and any configured ILogger, and one of them also closed a connection on the line above the one that opened it.

Dependencies

JasperFx 2.80.2 (#​5590) and Weasel 9.41.0 (#​5596, #​5576). Both carry Native AOT work of their own on the identity path — JasperFx's ValueTypeInfo wrappers and aggregate identity sources, Weasel's non-generic IIdentification facade.

🤖 Generated with Claude Code

https://claude.ai/code/session_01481eiEZg1Bv6pu4DrgPRg3

9.45.0

This one is largely the community's release. Four of the six changes below were found, diagnosed, or fixed by people outside the core team, and two of them are bugs that would have been very hard to find from the inside.

Community contributions

@​Hawxy — two LINQ regressions (#​5556). A captured nullable in a where clause was throwing: a Nullable<T> never survives boxing, so an empty one boxes to null and PropertyInfo.GetValue had no target, breaking the thoroughly ordinary where !captured.HasValue || x.Id == captured. HasValue and Value are now read off the boxed form. The same PR fixes literals in select statements surviving paging, stats, and version select clauses.

@​Hawxy — inline-to-async on an empty database (#​5561). FetchHighestEventSequenceNumber read mt_events_sequence.last_value, which PostgreSQL reports as 1 with is_called = false before anything has drawn from the sequence. SubscribeAsInlineToAsync used that as its starting position, so on an empty store the shard started at 1 against a high water mark of 0 and the agent failed with "The last committed number (1) cannot be higher than the high water mark (0)". A new store is exactly when you least want that.

@​tomasherceg — ordering after a grouped projection (#​5557, shipped as #​5563). CompileGroupBy transferred the downstream Limit and Offset but never the OrderingExpressions — even though the comment sitting over that block had claimed OrderBy was transferred for as long as it existed. A GroupBy(...).Select(...) that was then ordered came back in whatever order PostgreSQL felt like, with no order by in the SQL and no error, so a paged one took an arbitrary page.

Tomáš found it, diagnosed it, and landed the hard part — re-expressing the ordering against the projected shape rather than the document. He also flagged his own uncertainty about edge cases, which is what sent us looking and turned up two more: a scalar projection (Select(g => g.Key), Select(g => g.Count())) has no projected members, so ordering one threw instead of ordering by its single value; and OrderBySql() reported Invalid OrderBy() expression ''. Both now work. His commit is in the tree with his authorship.

@​chrisbbe — the identity probe's side effects (#​5562). The best bug report we have had in a while: a minimal repro, the stack trace, the mechanism, and a correct suggested fix.

Identity resolution handed its candidate filter to a traversal that applies it to every property and field, and only afterwards picks the id by [Identity] or by the name Id. That filter is not free to ask — for any public struct shaped like a strong-typed id it registers the type on the global PostgresqlProvider singleton and closes an open generic. So an ordinary non-identity property got remapped process-wide the moment its document or event type was mapped, turning an Optional<string> used only for a nickname into varchar for everything, LINQ included. Under Native AOT the generic construction brought startup down outright with a MissingMethodException.

Both probes now split into a pure shape test and the effectful registration; the traversal asks the cheap question and only the chosen member gets the expensive one.

⚠️ That exposed a second thing worth knowing about. RegisterValueType fills StoreOptions.ValueTypes but has never registered the Postgres mapping, so a value type used as a duplicated field rather than as an id only ever worked because the probe happened to reach it on some document. If you call opts.RegisterValueType<T>() you were doing the right thing and relying on an accident. That registration now belongs to RegisterValueType.

Performance

Batch reads are one round trip again (#​5550). JasperFx 2.79 added LoadManyAsync to IDocumentReadOperations and FetchManyForWriting to IEventStoreOperations, both default-implemented. The defaults are correct, and both make one round trip per id.

Marten has sixteen LoadManyAsync overloads and not one of them takes the token last, so the contract's (ids, token) call matched none of them and silently bound to the default. Nothing failed — the shared compliance suite loads 2,500 documents through it, 2,500 round trips at a time, passing.

	before	now
LoadManyAsync, 25 ids	25 round trips	1
LoadManyAsync, 2,500 ids	2,500	1
FetchManyForWriting, 10 streams	10	1

FetchManyForWriting is new public surface on Marten: one handle per id in the order asked for, a handle (not a gap) for a stream that does not exist yet, and each handle keeping its own starting version so SaveChangesAsync guards every stream it appended to and no other.

::: One lifecycle keeps the sequential shape
An aggregate projected with ProjectionLifecycle.Async is fetched inside begin transaction isolation level repeatable read read only, and PostgreSQL only accepts that as the first statement in a transaction — so two of them cannot share a batch. FetchManyForWriting detects that lifecycle and falls back to fetching sequentially: same results, same ordering, same per-stream guards, no round-trip saving. Inline, Live and Snapshot get the fast path.
:::

See FetchManyForWriting and Loading Documents by Id for the details.

Also

Dependency bumps from Dependabot: fast-uri (#​5558), brace-expansion (#​5559), dompurify (#​5560).

9.44.0

Bumps the JasperFx family to 2.79.1 and lands three fixes. Two of them change behaviour, one in a way that changes what a query returns.

Fixes

#​5549 — a nested Any() with a plain equality silently returned nothing. A sub-query is parsed against a member tree rooted at the element type, so inside Middles.Any(m => m.Bottoms.Any(...)) the Bottoms member reports d.data -> 'Bottoms' — within that parse, d.data stands for one Middle. Nothing in the member tree records that Bottoms lives under Middles; the containment filter is re-anchored when the enclosing Any() lifts it out. That re-anchoring moved the jsonb payload but left the locator pointing at the inner collection, so the query went out as

d.data -> 'Bottoms' @> '[{"Middles":[{"Name":"Bill"}]}]'

Well-formed SQL against a key the document does not have. No error, no rows.

Three shapes of the same query diverged, which is what made this hard to pin down from the outside: a sibling predicate (m.Color == Blue && m.Bottoms.Any(...)) built the containment through a different path and was always correct, StartsWith is not containment-eligible and fell to a jsonpath filter that re-rooted properly, and only the plain single-equality nested Any() was wrong.

Four more failures came out of the same defect once the generated SQL was dumped across every nesting shape:

Shape	Before
the nested Any() negated, or as an OR branch, or three levels deep	same wrong locator
m.Bottoms.Any(x) && m.Bottoms.Any(y) — the workaround suggested in the issue	the two merged into one payload element: one of the two values was silently dropped, and a single element had to satisfy both
three levels deep ending in a value collection	NotSupportedException
a value-collection Any()/Contains() beside a sibling predicate	NullReferenceException

⚠️ Behaviour change. t.Xs.Any(p) && t.Xs.Any(q) now matches when two different elements satisfy the two predicates. That is what the query asks for, and it is more rows than 9.43 returned. If you were relying on the old answer, you wanted t.Xs.Any(x => p(x) && q(x)).

Diagnostics surface (monitoring consoles)

jasperfx#​932 — DocumentTypesAsync lists document sub-classes. The contract was silent on this and the stores split: Polecat listed sub-classes, Marten and Fisher did not, and a store-agnostic type picker could not tell which answer it had. Settled in favour of listing them, because every member taking a documentTypeName already accepts a sub-class name and narrows to its rows — a picker that could not offer one was hiding a capability the contract guarantees.

Marten now emits an entry per registered sub-class alongside each mapped root. A sub-class entry carries its own mt_doc_type alias — the discriminator its rows actually hold, which is the string you pass back to QueryDocumentsAsync — and the root's schema, because the root's table is where those rows live. DocumentTypeRef.RootTypeName names the root and is null for a root itself; IsSubClass reads it.

⚠️ Behaviour change. A store with document hierarchies returns more entries from DocumentTypesAsync than it did in 9.43. IsSubClass tells them apart. RootTypeName is init-only, so the positional DocumentTypeRef shape a store compiled against an older JasperFx calls is unchanged.

Event sourcing

A composite projection could intermittently pause and stop advancing (jasperfx#​938). ProjectionExecution disposed its batch unconditionally through an await using. For a composite member that batch is the parent composite's, shared by design — so the member's scope-exit disposal raced the parent's execute, which then threw ObjectDisposedException out of Block.WaitForCompletionAsync and left the shard Paused with no progression row at all.

It takes a member on that path, so the exposed shape is a composite of an aggregation plus a plain event projection; an all-aggregation composite runs on GroupedProjectionExecution, which already guarded the disposal. Intermittent because the stages run in parallel and the race can fall either way — measured at roughly one run in eight on one such composite.

If you run composite projections with a non-aggregation member and have seen a shard quietly stop advancing, this is a strong candidate. Fixed in JasperFx 2.79.1.

Dependencies

JasperFx 2.79.1. Alongside jasperfx#​932 and jasperfx#​938 above: jasperfx#​930 adds LoadManyAsync to IDocumentReadOperations and FetchManyForWriting to IEventStoreOperations, jasperfx#​931 default-implements the 2.77 IDocumentStoreDiagnostics members so a store built against an older JasperFx still loads, and jasperfx#​933 ratchets abstract interface members so contract growth stays deliberate.

The new members arrive default-implemented and Marten has not yet overridden FetchManyForWriting / LoadManyAsync — the defaults are correct but call the single-id member in a loop. Batching them against Marten's existing batch-query API is tracked separately.

9.43.0

Bumps the JasperFx family to 2.78.0 and lands four issues, one of them a data-corruption fix worth reading even if you skip the rest.

Fixes

#​5539 — a zero-event quick append could permanently wedge a stream. mt_quick_append_events called with zero events read mt_streams.version without a lock and ended with a blind write-back, so under READ COMMITTED it could overwrite a concurrent appender's version and leave the stream row below its own events. Every later append then computed a version that already existed and failed on pk_mt_events_stream_and_version — permanently, with no recovery short of repairing the row by hand. A non-empty append could never do this: its first insert collides on that same primary key and rolls back, which is why only the empty call was exposed. The write-back is now skipped when nothing was appended, and uses greatest() so it can never lower a version whoever calls it.

Field context: a production console on 9.32.0 sat at mt_streams.version 608676 against max(mt_events.version) 608678 for 42 days, roughly 28 failed appends a minute. If you have a stream failing every append on that constraint, this is likely why.

#​5541 — ShardState.LastUpdated, liveness rather than progress. Sequence cannot distinguish caught up with nothing new from no longer maintained: both hold the same number forever. The progression row's last_updated now reaches ShardState and ProjectionProgressRow, and — the part that needed a product change — an idle high-water cycle now restamps the HighWaterMark row. Previously an idle cycle issued no SQL at all, so that stamp froze at the last real mark advance and read as "abandoned weeks ago" on a perfectly healthy store. The restamp never touches last_seq_id, so it cannot nudge the mark.

Diagnostics surface (monitoring consoles)

#​5543 — IDocumentStoreDiagnostics adopts the defined contract (jasperfx#​870). Five behaviours were previously "whatever the store happened to do", and Marten was on the wrong side of all five:

	Before	Now
Soft deletes	returned as live	excluded unless asked; a load by id returns the row flagged
Hierarchies	every sub-class in the table	filtered to the requested type; each row reports its own
Missing tenant	all tenants	the default tenant
"" tenant	a tenant literally named ""	the default tenant
Ids	id::text = @​id	converted to the stored identity type — uses the PK index, matches an upper-case Guid

Also: LoadDocumentAsync returning StoredDocument with metadata, populated DocumentQueryResult.Documents, a new IDocumentStoreDiagnosticsWriter (save-from-JSON and delete through a normal session, with an expected-version guard), DocumentStoreUsage.SerializerCasing, and structured index / duplicated-field descriptors. Query criteria Marten cannot yet translate are refused rather than silently ignored.

#​5544 — DocumentQueryOptions.AllTenants. The explicit replacement for the all-tenants read that #​5543 removed. Conjoined tenancy reads every tenant, ordered by tenant then id so paging cannot repeat a row. A store spreading tenants across databases refuses rather than quietly returning only the default tenant's rows.

⚠️ Behaviour change for diagnostics consumers: a null or blank TenantId now means the default tenant, not every tenant. If you relied on the old behaviour, set AllTenants = true.

Also

#​5542 — asynchronous aggregate events are ordered by stream sequence.

Internals: a diagnostic document read now resolves a tenant's database through TryFindDatabase rather than FindOrCreateDatabase, so asking a read-only question about an unknown tenant can no longer provision that tenant.

9.42.0

Mostly fixes, and two of them only became visible once the one underneath them was gone. Nothing here requires action on upgrade unless you use IsolationLevel.RepeatableRead or above, or batch a FetchForWriting for an Async-snapshot aggregate.

Migrations settle again on a long schema name

#​5536. ApplyAllDatabaseChangesOnStartup() against an already-migrated schema could fail with:

42710: constraint "fkey_mt_events_stream_id" for relation "mt_events" already exists

The foreign key was not the problem. PostgreSQL truncates identifiers at 63 characters, so a longer DatabaseSchemaName was stored truncated while Marten went on querying for the name it had asked for — found none of its objects, concluded they were all missing, and re-issued DDL the server resolved against the truncated schema, where they already existed. The first apply passed and the second failed, with an error pointing nowhere near the schema name.

DatabaseSchemaName is now truncated to 63 characters so the two sides agree. This does not move anyone's data: the server was already truncating it, and Marten now simply uses the name the server actually stored. Two distinct long names sharing their first 63 characters still collide, exactly as they already do in PostgreSQL.

The apply-changes lock waits long enough to be useful

#​5529. The advisory lock guarding startup migrations retried on a fixed 50 / 100 / 250ms ladder — about 400ms to win it. That is ample for the multi-replica rolling deploy it was designed for, where the loser only has to outlast a peer's finished migration. It is not enough when more than one store shares a database inside one host, where the loser has to outlast a migration that is still running: it failed startup, and the message's own advice (ResourceMigrationFailureMode.ContinueOnFailures) would have started the application against a half-migrated schema.

New knob, defaulting to 10 seconds:

opts.ApplyChangesLockTimeout = 30.Seconds();   // many stores on one database, or a large schema

This was held back until it could be measured. While weasel#​659 was unfixed the lock was stranded by any migration that threw, and a longer wait provably changed nothing. Weasel 9.37.0 releases it on the failure path, and only then did the residue show up as a genuine race worth budgeting for.

⚠️ No write retry from RepeatableRead upwards

#​5528, completing what 9.41.0 started. Marten's retry replays the operations it has already computed, not the application code that computed them — and from RepeatableRead up, the session's transaction is pinned to one snapshot. So any successful replay commits decisions derived from a snapshot that no longer exists. That is exactly the silent lost update 9.41.0 fixed for 40001, and 40P01 (deadlock) had the same flaw for the same structural reason.

The write-retry pipeline is now skipped entirely for RepeatableRead, Serializable and Snapshot. This is deliberately broader than refusing those two SQLSTATEs: class 53, 55, 57P03 and 58 all abort a snapshot-holding transaction too, so singling out class 40 would have left the identical hole open one error code over.

If you use those isolation levels, expect to see failures surface that were previously retried away. Handle them by re-reading and recomputing — the only place a snapshot conflict can be resolved. ReadCommitted is the default and is unchanged: it takes a fresh snapshot per statement, so replaying precomputed SQL still means what it meant, and every existing application keeps full retry behaviour.

A batched Async-snapshot FetchForWriting says what it needs

#​5535. For an aggregate projected with ProjectionLifecycle.Async, the non-exclusive FetchForWriting wraps its reads in begin transaction isolation level repeatable read read only … end so they share one snapshot — and PostgreSQL accepts that only as the first statement in a transaction. Enlisted after anything else in a batch, it failed at Execute() with 25001: SET TRANSACTION ISOLATION LEVEL must be called before any query, naming an isolation level the caller never mentioned and saying nothing about ordering. Nothing about CreateBatchQuery() hints that one of its members has to go first.

It is now refused at the enlisting call, with a message that names the aggregate and the constraint. The position that worked still works.

Dependencies

Weasel 9.37.0, whose weasel#​659 is the reason most of #​5529 went away: ApplyAllConfiguredChangesToDatabaseAsync released the global migration lock only on its success paths, so a migration that threw left it held and locked every other replica out of migrating — while the node that stranded it reported nothing. Disposing the connection was not enough, because Npgsql resets a pooled connection when it is next used rather than when it is returned, so the lock outlived the apply for as long as that connection sat idle.

Also in 9.37.0, and worth reading if you use them: SQL Server 2025 JSON indexes are no longer emitted as DROP INDEX on every apply (weasel#​661), Oracle descending indexes and co-migrated views settle (weasel#​660), TableDelta.HasChanges() answers instead of throwing for a table that does not exist yet (weasel#​658), and the reconnection loop no longer abandons a connection per attempt (weasel#​664).

Housekeeping

DISABLE_TEST_PARALLELIZATION is gone from the CI workflow and the contributor docs. Nothing ever read it, so it looked like a control and was not one — including to us, while diagnosing #​5529. Test parallelisation is disabled by CollectionBehavior in AssemblyInfo.cs, and both files now say where to change it.

9.41.0

Upgrade if you use IsolationLevel.Serializable. The first item below is a silent lost update, and it has been present since the write-retry pipeline shipped. The two items after it change behaviour you may be relying on.

🛑 Data integrity: Serializable sessions could silently lose an update

#​5528. A session opened with IsolationLevel.Serializable (or RepeatableRead) did not reliably protect against a lost update. PostgreSQL detected the write conflict correctly and Marten discarded the detection by retrying.

Two serializable sessions each load the same document at Amount = 100. One commits 100 - 500. The other should be refused with ConcurrentUpdateException; instead it committed 100 - 350 on top, and the first session's write was gone with no error raised anywhere. From the server's own log:

[14197] ERROR:  could not serialize access due to concurrent update
[14197] ROLLBACK
[14196] BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE    -- the replay
[14196] insert ... on conflict (id) do update ...         -- same values, same mt_version
[14196] COMMIT

WriteRetryClassifier (#​5262) listed 40001 serialization_failure as safe to replay, on the reasoning that the server had rolled the transaction back and said so — which is true, and turned out to be necessary but not sufficient. A replay re-issues the operations already computed, rather than re-running the application code that produced them, and a serialization failure means precisely that the snapshot those operations were derived from is no longer a valid basis for them. The replay opens a new transaction with a fresh snapshot, so the conflict is gone and the write lands.

40001 is now never replayed and surfaces as ConcurrentUpdateException, which is what Marten already translated it to. If you opted into Serializable you should expect to start seeing that exception — handle it by re-reading and recomputing, which is the only place the conflict can be resolved. Nothing inside Marten requests these isolation levels, so the async daemon and every default ReadCommitted session are unaffected.

40P01 deadlock_detected stays retryable deliberately: a deadlock aborts over lock ordering rather than a rejected snapshot, and replaying it is the textbook remedy at ReadCommitted. A deadlock retry under Serializable replays stale-snapshot work for the same structural reason, and the honest fix needs the isolation level plumbed into the classifier — recorded as a known gap rather than guessed at.

This went unnoticed because the test that catches it lives in StressTests, which has had no CI job since 2026-08-08.

⚠️ Behaviour change: the HotCold leadership lock is session-scoped again

#​5526. Events.UseAdvisoryLockTransaction now defaults to false, so HotCold leader election uses a session-scoped pg_try_advisory_lock rather than a transaction-scoped pg_try_advisory_xact_lock. The transaction-scoped lock had been the default since 8.37.3 (April 2026).

The reason is what the transaction-scoped lock costs while it works: the leader holds an open transaction for as long as it holds leadership, which on a long-lived daemon is an indefinitely long-running transaction sitting on the connection — with everything that implies for vacuum and for anything watching transaction age.

The transaction-scoped lock is still the better fit behind PgBouncer in transaction pooling mode, which can hand a session-scoped lock's server connection to another client. If that is your deployment, opt back in explicitly:

builder.Services.AddMarten(opts =>
{
    opts.Connection(connectionString);
    opts.Events.UseAdvisoryLockTransaction = true;
})
.AddAsyncDaemon(DaemonMode.HotCold);

⚠️ Breaking: DefaultTenantUsageDisabledException is no longer a MartenException

#​5514. Marten.Exceptions.DefaultTenantUsageDisabledException now derives from JasperFx.Events.DefaultTenantUsageDisabledException.

JasperFx.Events carries this exception so that code can handle the refusal once across Critter Stack stores, and its own contract is that stores subclass it. Polecat did; Marten did not. The consequence was not an error anywhere — a store-agnostic catch (JasperFx.Events.DefaultTenantUsageDisabledException) compiled, read as if it handled the refusal, and let it through unhandled on Marten only. That is the failure mode this fixes.

Multiple inheritance is not available, so it is one base or the other, and the cross-store catch was judged worth more than the marker base. If you rely on a broad catch (MartenException) to handle this refusal, it will no longer be caught — catch the exception itself, or the JasperFx base. The message is unchanged, including the single-argument overload's behaviour of appending to the standard prefix.

Also gone with the reparenting: the protected (SerializationInfo, StreamingContext) constructor, because the JasperFx base declares none to chain to. Binary serialization of exceptions has been obsolete since .NET 8.
... (truncated)

9.40.0

Minor rather than patch for one reason: the source-generated DetermineAction now decides one action per batch rather than per event. See the behaviour change below before upgrading if you archive streams from a projection.

⚠️ Behaviour changes

Archiving projections: one action per batch, not per event (JasperFx/jasperfx#​889, via the JasperFx 2.75.2 bump). The source-generated DetermineAction used to decide per event; it now decides once per batch. This changes what an archiving projection does when a single batch mixes an archive with later events for the same stream. StreamArchivingCompliance gained facts for it and Marten passes them, but if you depend on the old per-event evaluation, test before upgrading.

TenantIdStyle is now applied where the tenant id is stamped and keyed, not only where a tenant is resolved (#​5516). Under ForceLowerCase, these three previously wrote or matched the raw id:

• BulkInsertEventsAsync / BulkInsertEventStreamAsync resolved the right database or partition and then stamped the raw id on every mt_streams / mt_events row — rows invisible to any normalised read under conjoined tenancy, and the wrong key inside the right partition under UseTenantPartitionedEvents.
• TenantIsOneOf(...) filtered on the raw values, so a mixed-case id matched nothing.
• DeleteAllTenantDataAsync used the raw id as its DELETE ... WHERE tenant_id = :p parameter, so it matched no rows and reported success — the one to look at hardest, since callers are usually honouring an erasure request.

If you have been calling these with mixed-case tenant ids, data already written under the raw casing stays where it is; it will not be found by a normalised read. ForTenant(string) also now normalises its nested-session cache key, which makes ForTenant("RED") and ForTenant("red") one session rather than two.

Event store

• IEventStore.OpenReadOnlyEventStore(tenantId) is implemented (#​5513). With Advanced.DefaultTenantUsageEnabled = false — the automatic state once database-per-tenant tenancy is configured — the entire IReadOnlyEventStore surface was unreachable, because the tenant-less overload opens the store's default session and is refused before any tenant scope applies. That is why QueryStreamStates(tenantId)'s own parameter could not work around it. A null tenant keeps the previous store-global behaviour.
• Diagnostic event-store reads answer "no results" instead of throwing (#​5511, #​5512), decided from the database rather than from configuration.
• Progression and dead-letter reads answer nothing for an event store nothing provisions (#​5509, #​5510).

Diagnosing a missing source-generated dispatcher

The JasperFx 2.75.2 bump (#​5518) carries three changes that came out of #​5495, where a user's aggregates compiled with no dispatcher and the runtime message could not tell them why:

• The generator now leaves [assembly: JasperFxSourceGeneratorApplied] in every assembly it processes, so "the generator never ran in that assembly" — a csproj problem — is distinguishable at runtime from "the generator ran and declined your type" — a code-shape problem. The exception says which.
• Two copies of the generator in one compilation no longer collide with CS0433. This happens when a project references the standalone JasperFx.Events.SourceGenerator package as well as Marten, which bundles it: both copies emit identical file paths and the file-scoped evolvers mangle to the same name. If you hit that error — recognisable because it names the same assembly on both sides — remove the standalone package reference; Marten already carries the analyzer.
• Opt in to a build-time check with <JasperFxEventsRequireSourceGenerator>true</JasperFxEventsRequireSourceGenerator> on projects that declare aggregates, and a missing analyzer becomes build error JFXEVT900 rather than a failure at the first FetchForWriting.

Compliance coverage

Marten is now enrolled in DocumentConjoinedTenancyCompliance (#​5517) — the first shared document coverage of conjoined tenancy on any store — with all 10 facts running. ConjoinedEventTenancyCompliance goes from 16 passing with 2 skipped to 18 passing with none, the two skips having been waiting on the read-only overload above.

Two of these enrollments exposed that Marten's own commit-listener compliance facts had been passing vacuously — the harness never installed the listener the suites register, so "no phantom deletion was reported" was trivially true of a store reporting nothing at all. Fixed in the #​5518 bump; no product change was needed, and both halves of that fact now pass for real.

Dependencies

JasperFx 2.75.2 and Weasel 9.35.2.

Weasel 9.35.x is mostly EF Core and SQL Server work, plus weasel#​634: an exhausted DropSchema retry is now reported instead of returning success.

Docs

The bundled analyzer does flow transitively across a ProjectReference (#​5508) — the composite-configuration page claimed the opposite. The claim was true of the standalone analyzer package, which Marten sets PrivateAssets="all" on, but #​4557 bundles the analyzer DLL into Marten's own package and that copy flows.

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[sonarqubecloud]

Quality Gate passed

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[dependabot]

Superseded by #36.