diff --git a/crates/pixi_build_frontend/src/backend/in_memory/passthrough.rs b/crates/pixi_build_frontend/src/backend/in_memory/passthrough.rs
index b1c1fc3226..598e6343f5 100644
--- a/crates/pixi_build_frontend/src/backend/in_memory/passthrough.rs
+++ b/crates/pixi_build_frontend/src/backend/in_memory/passthrough.rs
@@ -13,7 +13,7 @@ use pixi_build_types::{
         initialize::InitializeParams,
     },
 };
-use rattler_conda_types::{Platform, Version, package::IndexJson};
+use rattler_conda_types::{PackageName, Platform, Version, package::IndexJson};
 use serde::Deserialize;
 
 use crate::{
@@ -64,7 +64,19 @@ impl InMemoryBackend for PassthroughBackend {
         Ok(CondaOutputsResult {
             outputs: vec![CondaOutput {
                 metadata: CondaOutputMetadata {
-                    name: self.project_model.name.parse().unwrap(),
+                    name: self
+                        .project_model
+                        .name
+                        .as_ref()
+                        .map(|name| PackageName::try_from(name.as_str()).unwrap())
+                        .unwrap_or_else(|| {
+                            self.index_json
+                                .as_ref()
+                                .map(|j| j.name.clone())
+                                .unwrap_or_else(|| {
+                                    PackageName::try_from("pixi-package_name").unwrap()
+                                })
+                        }),
                     version: self
                         .project_model
                         .version
diff --git a/crates/pixi_build_type_conversions/src/project_model.rs b/crates/pixi_build_type_conversions/src/project_model.rs
index 33a70c3908..4040ca850a 100644
--- a/crates/pixi_build_type_conversions/src/project_model.rs
+++ b/crates/pixi_build_type_conversions/src/project_model.rs
@@ -173,7 +173,7 @@ pub fn to_project_model_v1(
 ) -> Result<pbt::ProjectModelV1, SpecConversionError> {
     let project = pbt::ProjectModelV1 {
         name: manifest.package.name.clone(),
-        version: Some(manifest.package.version.clone()),
+        version: manifest.package.version.clone(),
         description: manifest.package.description.clone(),
         authors: manifest.package.authors.clone(),
         license: manifest.package.license.clone(),
diff --git a/crates/pixi_build_types/src/lib.rs b/crates/pixi_build_types/src/lib.rs
index 6e152317cd..efe9e8d992 100644
--- a/crates/pixi_build_types/src/lib.rs
+++ b/crates/pixi_build_types/src/lib.rs
@@ -23,13 +23,17 @@ use rattler_conda_types::{
 };
 use serde::{Deserialize, Serialize};
 
+// Version 0: Initial version
+// Version 1: Added conda/outputs and conda/build_v1
+// Version 2: Name in project models can be `None`.
+
 /// The constraint for the pixi build api version package
 /// Adding this constraint when solving a pixi build backend environment ensures
 /// that a backend is selected that uses the same interface version as Pixi does
 pub static PIXI_BUILD_API_VERSION_NAME: LazyLock<PackageName> =
     LazyLock::new(|| PackageName::new_unchecked("pixi-build-api-version"));
 pub const PIXI_BUILD_API_VERSION_LOWER: u64 = 0;
-pub const PIXI_BUILD_API_VERSION_CURRENT: u64 = 1;
+pub const PIXI_BUILD_API_VERSION_CURRENT: u64 = 2;
 pub const PIXI_BUILD_API_VERSION_UPPER: u64 = PIXI_BUILD_API_VERSION_CURRENT + 1;
 pub static PIXI_BUILD_API_VERSION_SPEC: LazyLock<VersionSpec> = LazyLock::new(|| {
     VersionSpec::Group(
@@ -85,9 +89,17 @@ impl PixiBuildApiVersion {
                 provides_conda_build_v1: Some(true),
                 ..Self(0).expected_backend_capabilities()
             },
+            2 => BackendCapabilities {
+                ..Self(1).expected_backend_capabilities()
+            },
             _ => BackendCapabilities::default(),
         }
     }
+
+    /// Returns true if this version of the protocol supports the name field in the project model to be `None`.
+    pub fn supports_name_none(&self) -> bool {
+        self.0 >= 2
+    }
 }
 
 impl Display for PixiBuildApiVersion {
diff --git a/crates/pixi_build_types/src/project_model.rs b/crates/pixi_build_types/src/project_model.rs
index 45dab31eae..ec7c5f654f 100644
--- a/crates/pixi_build_types/src/project_model.rs
+++ b/crates/pixi_build_types/src/project_model.rs
@@ -74,7 +74,7 @@ pub type SourcePackageName = String;
 #[serde(rename_all = "camelCase")]
 pub struct ProjectModelV1 {
     /// The name of the project
-    pub name: String,
+    pub name: Option<String>,
 
     /// The version of the project
     pub version: Option<Version>,
@@ -176,17 +176,18 @@ impl TargetsV1 {
 }
 
 impl IsDefault for TargetsV1 {
-    fn is_default(&self) -> bool {
-        self.is_empty()
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        if !self.is_empty() { Some(self) } else { None }
     }
 }
 
 impl<T: IsDefault> IsDefault for Option<T> {
-    fn is_default(&self) -> bool {
-        match self {
-            None => true,
-            Some(value) => value.is_default(),
-        }
+    type Item = T::Item;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        self.as_ref()?.is_non_default()
     }
 }
 
@@ -219,8 +220,10 @@ impl TargetV1 {
 }
 
 impl IsDefault for TargetV1 {
-    fn is_default(&self) -> bool {
-        self.is_empty()
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        if !self.is_empty() { Some(self) } else { None }
     }
 }
 
@@ -601,8 +604,10 @@ impl Hash for GitReferenceV1 {
 }
 
 impl IsDefault for GitReferenceV1 {
-    fn is_default(&self) -> bool {
-        false // Never skip GitReferenceV1 fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip GitReferenceV1 fields
     }
 }
 
@@ -642,7 +647,7 @@ mod tests {
     fn test_hash_stability_with_default_values() {
         // Create a minimal ProjectModelV1 instance
         let mut project_model = ProjectModelV1 {
-            name: "test-project".to_string(),
+            name: Some("test-project".to_string()),
             version: None,
             description: None,
             authors: None,
@@ -698,7 +703,7 @@ mod tests {
     fn test_hash_changes_with_meaningful_values() {
         // Create a minimal ProjectModelV1 instance
         let mut project_model = ProjectModelV1 {
-            name: "test-project".to_string(),
+            name: Some("test-project".to_string()),
             version: None,
             description: None,
             authors: None,
@@ -993,14 +998,14 @@ mod tests {
     fn test_hash_collision_bug_project_model() {
         // Test the same issue in ProjectModelV1
         let project1 = ProjectModelV1 {
-            name: "test".to_string(),
+            name: Some("test".to_string()),
             description: Some("test description".to_string()),
             license: None,
             ..Default::default()
         };
 
         let project2 = ProjectModelV1 {
-            name: "test".to_string(),
+            name: Some("test".to_string()),
             description: None,
             license: Some("test description".to_string()),
             ..Default::default()
diff --git a/crates/pixi_build_types/src/stable_hash.rs b/crates/pixi_build_types/src/stable_hash.rs
index ca6c789a55..506f00e94d 100644
--- a/crates/pixi_build_types/src/stable_hash.rs
+++ b/crates/pixi_build_types/src/stable_hash.rs
@@ -35,7 +35,9 @@ impl Hash for FieldDiscriminant {
 /// Trait to determine if a value should be considered "default" and thus skipped in hash calculations.
 /// This helps maintain forward/backward compatibility by only including discriminants for meaningful values.
 pub(crate) trait IsDefault {
-    fn is_default(&self) -> bool;
+    type Item;
+
+    fn is_non_default(&self) -> Option<&Self::Item>;
 }
 
 /// A dyn-compatible hashing trait that works with any hasher type
@@ -66,9 +68,12 @@ impl<'a, H: std::hash::Hasher> StableHashBuilder<'a, H> {
 
     /// Add a field to the hash if it's not in its default state.
     /// Fields will be automatically sorted alphabetically before hashing.
-    pub fn field<T: Hash + IsDefault>(mut self, name: &'static str, value: &'a T) -> Self {
-        if !value.is_default() {
-            self.fields.insert(name, value);
+    pub fn field<T: IsDefault>(mut self, name: &'static str, value: &'a T) -> Self
+    where
+        T::Item: Hash,
+    {
+        if let Some(item) = value.is_non_default() {
+            self.fields.insert(name, item);
         }
         self
     }
@@ -83,61 +88,81 @@ impl<'a, H: std::hash::Hasher> StableHashBuilder<'a, H> {
 }
 
 impl<K, V> IsDefault for OrderMap<K, V> {
-    fn is_default(&self) -> bool {
-        self.is_empty()
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        if !self.is_empty() { Some(self) } else { None }
     }
 }
 
 impl IsDefault for String {
-    fn is_default(&self) -> bool {
-        false // Never skip required string fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip required string fields
     }
 }
 
 impl IsDefault for url::Url {
-    fn is_default(&self) -> bool {
-        false // Never skip required URL fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip required URL fields
     }
 }
 
 impl IsDefault for std::path::PathBuf {
-    fn is_default(&self) -> bool {
-        false // Never skip PathBuf fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip PathBuf fields
     }
 }
 
 impl<T> IsDefault for Vec<T> {
-    fn is_default(&self) -> bool {
-        self.is_empty()
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        if !self.is_empty() { Some(self) } else { None }
     }
 }
 
 impl IsDefault for rattler_conda_types::Version {
-    fn is_default(&self) -> bool {
-        false // Never skip version fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip version fields
     }
 }
 
 impl IsDefault for rattler_conda_types::StringMatcher {
-    fn is_default(&self) -> bool {
-        false // Never skip StringMatcher fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip StringMatcher fields
     }
 }
 
 impl IsDefault for rattler_conda_types::BuildNumberSpec {
-    fn is_default(&self) -> bool {
-        false // Never skip BuildNumberSpec fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip BuildNumberSpec fields
     }
 }
 
 impl IsDefault for rattler_conda_types::VersionSpec {
-    fn is_default(&self) -> bool {
-        false // Never skip VersionSpec fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip VersionSpec fields
     }
 }
 
 impl<U, T: rattler_digest::digest::generic_array::ArrayLength<U>> IsDefault for GenericArray<U, T> {
-    fn is_default(&self) -> bool {
-        false // Never skip digest output fields
+    type Item = Self;
+
+    fn is_non_default(&self) -> Option<&Self::Item> {
+        Some(self) // Never skip digest output fields
     }
 }
diff --git a/crates/pixi_command_dispatcher/src/command_dispatcher/instantiate_backend.rs b/crates/pixi_command_dispatcher/src/command_dispatcher/instantiate_backend.rs
index 46df117d37..505e6b82dd 100644
--- a/crates/pixi_command_dispatcher/src/command_dispatcher/instantiate_backend.rs
+++ b/crates/pixi_command_dispatcher/src/command_dispatcher/instantiate_backend.rs
@@ -151,6 +151,19 @@ impl CommandDispatcher {
             api_version,
         );
 
+        // Make sure that the project model is compatible with the API version.
+        if !api_version.supports_name_none()
+            && spec
+                .init_params
+                .project_model
+                .as_ref()
+                .is_some_and(|p| p.name.is_none())
+        {
+            return Err(CommandDispatcherError::Failed(
+                InstantiateBackendError::SpecConversionError(SpecConversionError::MissingName),
+            ));
+        }
+
         JsonRpcBackend::setup(
             source_dir,
             spec.init_params.manifest_path,
diff --git a/crates/pixi_core/src/lock_file/satisfiability/mod.rs b/crates/pixi_core/src/lock_file/satisfiability/mod.rs
index 82be451cf0..742fe69a43 100644
--- a/crates/pixi_core/src/lock_file/satisfiability/mod.rs
+++ b/crates/pixi_core/src/lock_file/satisfiability/mod.rs
@@ -1142,6 +1142,9 @@ pub(crate) async fn verify_package_platform_satisfiability(
                                         ParseChannelError::InvalidPath(p).into()
                                     }
                                     SpecConversionError::InvalidChannel(_name, p) => p.into(),
+                                    SpecConversionError::MissingName => {
+                                        ParseMatchSpecError::MissingPackageName
+                                    }
                                 };
                                 return Err(Box::new(PlatformUnsat::FailedToParseMatchSpec(
                                     name.as_source().to_string(),
@@ -1951,7 +1954,6 @@ mod tests {
 
     #[rstest]
     #[tokio::test]
-    #[cfg_attr(not(feature = "slow_integration_tests"), ignore)]
     async fn test_example_satisfiability(
         #[files("../../examples/**/p*.toml")] manifest_path: PathBuf,
     ) {
diff --git a/crates/pixi_core/src/lock_file/satisfiability/snapshots/pixi_core__lock_file__satisfiability__tests__failing_satisiability@source-dependency-changed-project-model.snap b/crates/pixi_core/src/lock_file/satisfiability/snapshots/pixi_core__lock_file__satisfiability__tests__failing_satisiability@source-dependency-changed-project-model.snap
index 50d0fdb3ad..813a838e08 100644
--- a/crates/pixi_core/src/lock_file/satisfiability/snapshots/pixi_core__lock_file__satisfiability__tests__failing_satisiability@source-dependency-changed-project-model.snap
+++ b/crates/pixi_core/src/lock_file/satisfiability/snapshots/pixi_core__lock_file__satisfiability__tests__failing_satisiability@source-dependency-changed-project-model.snap
@@ -1,7 +1,8 @@
 ---
-source: src/lock_file/satisfiability/mod.rs
+source: crates/pixi_core/src/lock_file/satisfiability/mod.rs
 expression: s
+snapshot_kind: text
 ---
 environment 'default' does not satisfy the requirements of the project for platform 'linux-64'
     Diagnostic severity: error
-    Caused by: the input hash for 'child-package' (f0d841a0cfd56becd0041a6bbcd215a19ce9c34c08530a98b642381af8ebd32a) does not match the hash in the lock-file (64a8e9eb88c4f6e944a37279a38a47fe7872454fb62bcafad63d200aef4b4a05)
+    Caused by: the input hash for 'child-package' (6a7fcb5c9f728504123fff40635207fb963b77f26b1a2dffb2993efa7f81559d) does not match the hash in the lock-file (64a8e9eb88c4f6e944a37279a38a47fe7872454fb62bcafad63d200aef4b4a05)
diff --git a/crates/pixi_glob/src/snapshots/pixi_glob__glob_hash__test__glob_hash_case_1_satisfiability.snap b/crates/pixi_glob/src/snapshots/pixi_glob__glob_hash__test__glob_hash_case_1_satisfiability.snap
index 6f4d79766a..30d9dc7ece 100644
--- a/crates/pixi_glob/src/snapshots/pixi_glob__glob_hash__test__glob_hash_case_1_satisfiability.snap
+++ b/crates/pixi_glob/src/snapshots/pixi_glob__glob_hash__test__glob_hash_case_1_satisfiability.snap
@@ -1,10 +1,11 @@
 ---
 source: crates/pixi_glob/src/glob_hash.rs
 expression: snapshot
+snapshot_kind: text
 ---
 Globs:
 - tests/data/satisfiability/source-dependency/**/*
-Hash: 4ae275fa46ad1fa335806cd37767a8fe530046fb38aea40b24527fddf3a769b8
+Hash: 15638d2bfdb15971bb19d0593ee872437fb6a5c88b143e01f3044e473888e39c
 Matched files:
 - tests/data/satisfiability/source-dependency/child-package/pixi.toml
 - tests/data/satisfiability/source-dependency/pixi.lock
diff --git a/crates/pixi_manifest/src/discovery.rs b/crates/pixi_manifest/src/discovery.rs
index ae260fa845..e2b49cb4b6 100644
--- a/crates/pixi_manifest/src/discovery.rs
+++ b/crates/pixi_manifest/src/discovery.rs
@@ -631,7 +631,14 @@ mod test {
                         writeln!(
                             &mut snapshot,
                             "Package: {} @ {}",
-                            &package.value.package.name, &package.value.package.version,
+                            &package.clone().value.package.name.unwrap_or("None".into()),
+                            &package
+                                .value
+                                .package
+                                .version
+                                .as_ref()
+                                .map(|v| v.to_string())
+                                .unwrap_or_else(|| "None".to_string()),
                         )
                         .unwrap();
                     }
@@ -656,7 +663,6 @@ mod test {
     #[case::missing_table_pixi_manifest("missing-tables/pixi.toml")]
     #[case::missing_table_pyproject_manifest("missing-tables-pyproject/pyproject.toml")]
     #[case::split_package("split_package/good/package")]
-    #[case::split_package("split_package/bad/package")]
     fn test_explicit_workspace_discoverer(#[case] subdir: &str) {
         let test_data_root = dunce::canonicalize(
             Path::new(env!("CARGO_MANIFEST_DIR")).join("../../tests/data/workspace-discovery"),
@@ -696,7 +702,14 @@ mod test {
                     writeln!(
                         &mut snapshot,
                         "Package: {} @ {}",
-                        &package.value.package.name, &package.value.package.version,
+                        &package.clone().value.package.name.unwrap_or("None".into()),
+                        &package
+                            .value
+                            .package
+                            .version
+                            .as_ref()
+                            .map(|v| v.to_string())
+                            .unwrap_or_else(|| "None".to_string()),
                     )
                     .unwrap();
                 }
diff --git a/crates/pixi_manifest/src/package.rs b/crates/pixi_manifest/src/package.rs
index 66bd0d2562..2ea120d39e 100644
--- a/crates/pixi_manifest/src/package.rs
+++ b/crates/pixi_manifest/src/package.rs
@@ -7,10 +7,10 @@ use url::Url;
 #[derive(Debug, Clone)]
 pub struct Package {
     /// The name of the project
-    pub name: String,
+    pub name: Option<String>,
 
     /// The version of the project
-    pub version: Version,
+    pub version: Option<Version>,
 
     /// An optional project description
     pub description: Option<String>,
@@ -39,7 +39,7 @@ pub struct Package {
 
 impl Package {
     /// Creates a new package with the given name and version.
-    pub fn new(name: String, version: Version) -> Self {
+    pub fn new(name: Option<String>, version: Option<Version>) -> Self {
         Self {
             name,
             version,
diff --git a/crates/pixi_manifest/src/snapshots/pixi_manifest__discovery__test__explicit_workspace_discoverer@split_package_bad_package.snap b/crates/pixi_manifest/src/snapshots/pixi_manifest__discovery__test__explicit_workspace_discoverer@split_package_bad_package.snap
deleted file mode 100644
index 4fadbb9458..0000000000
--- a/crates/pixi_manifest/src/snapshots/pixi_manifest__discovery__test__explicit_workspace_discoverer@split_package_bad_package.snap
+++ /dev/null
@@ -1,11 +0,0 @@
----
-source: crates/pixi_manifest/src/discovery.rs
-expression: snapshot
----
-  × missing field 'name' in table
-   ╭─[<CARGO_ROOT>/tests/data/workspace-discovery/split_package/bad/package/pixi.toml:6:1]
- 5 │
- 6 │ ╭─▶ [package.build.backend]
- 7 │ │   name = "pixi-build-rattler-build"
- 8 │ ╰─▶ version = "0.1.*"
-   ╰────
diff --git a/crates/pixi_manifest/src/toml/manifest.rs b/crates/pixi_manifest/src/toml/manifest.rs
index 17af3995f1..698d843528 100644
--- a/crates/pixi_manifest/src/toml/manifest.rs
+++ b/crates/pixi_manifest/src/toml/manifest.rs
@@ -617,52 +617,6 @@ mod test {
         ));
     }
 
-    #[test]
-    fn test_missing_version() {
-        assert_snapshot!(expect_parse_failure(
-            r#"
-        [workspace]
-        name = "foo"
-        channels = []
-        platforms = []
-        preview = ["pixi-build"]
-
-        [package]
-        name = { workspace = true }
-
-        [package.build]
-        backend = { name = "foobar", version = "*" }
-        "#,
-        ));
-    }
-
-    #[test]
-    fn test_missing_package_name() {
-        assert_snapshot!(expect_parse_failure(
-            r#"
-        [workspace]
-        channels = []
-        platforms = []
-        preview = ["pixi-build"]
-
-        [package]
-        # Since workspace doesnt define a name we expect an error here.
-
-        [package.build]
-        backend = { name = "foobar", version = "*" }
-        "#,
-        ), @r###"
-         × missing field 'name' in table
-          ╭─[pixi.toml:7:9]
-        6 │
-        7 │         [package]
-          ·         ──────────
-        8 │         # Since workspace doesnt define a name we expect an error here.
-        9 │
-          ╰────
-        "###);
-    }
-
     #[test]
     fn test_workspace_name_from_package() {
         let workspace_manifest = WorkspaceManifest::from_toml_str(
diff --git a/crates/pixi_manifest/src/toml/package.rs b/crates/pixi_manifest/src/toml/package.rs
index 7b0dc597ea..3f22ac19c8 100644
--- a/crates/pixi_manifest/src/toml/package.rs
+++ b/crates/pixi_manifest/src/toml/package.rs
@@ -5,7 +5,7 @@ pub use pixi_toml::TomlFromStr;
 use pixi_toml::{DeserializeAs, Same, TomlIndexMap, TomlWith};
 use rattler_conda_types::Version;
 use thiserror::Error;
-use toml_span::{DeserError, Error, ErrorKind, Span, Spanned, Value, de_helpers::TableHelper};
+use toml_span::{DeserError, Span, Spanned, Value, de_helpers::TableHelper};
 use url::Url;
 
 use crate::{
@@ -270,43 +270,6 @@ pub enum PackageError {
 }
 
 impl TomlPackage {
-    /// Helper function to resolve a required field with 3-tier hierarchy:
-    /// 1. Direct value (from package)
-    /// 2. Workspace inheritance (from workspace)
-    /// 3. Package defaults (from [project] section if the manifest is a
-    ///    `pyproject.toml`)
-    /// 4. Error if missing at all levels
-    fn resolve_required_field_with_defaults<T>(
-        field: Option<WorkspaceInheritableField<T>>,
-        workspace_value: Option<T>,
-        default_value: Option<T>,
-        field_name: &'static str,
-        package_span: Span,
-    ) -> Result<T, TomlError> {
-        match field {
-            Some(WorkspaceInheritableField::Value(v)) => Ok(v),
-            Some(WorkspaceInheritableField::Workspace(span)) => workspace_value.ok_or_else(|| {
-                GenericError::new(format!("the workspace does not define a '{}'", field_name))
-                    .with_span(span.into())
-                    .into()
-            }),
-            Some(WorkspaceInheritableField::NotWorkspace(span)) => {
-                Err(workspace_cannot_be_false().with_span(span.into()).into())
-            }
-            None => {
-                // Fall back to package defaults
-                default_value.ok_or(
-                    Error {
-                        kind: ErrorKind::MissingField(field_name),
-                        span: package_span,
-                        line_info: None,
-                    }
-                    .into(),
-                )
-            }
-        }
-    }
-
     /// Helper function to resolve an optional field with 3-tier hierarchy:
     /// 1. Direct value (from package)
     /// 2. Workspace inheritance (from workspace) - ERROR if explicitly
@@ -358,19 +321,17 @@ impl TomlPackage {
 
         // Resolve fields with 3-tier hierarchy: direct → workspace → package defaults →
         // error
-        let name = Self::resolve_required_field_with_defaults(
+        let name = Self::resolve_optional_field_with_defaults(
             self.name,
             workspace.name,
             package_defaults.name,
             "name",
-            self.span,
         )?;
-        let version = Self::resolve_required_field_with_defaults(
+        let version = Self::resolve_optional_field_with_defaults(
             self.version,
             workspace.version,
             package_defaults.version,
             "version",
-            self.span,
         )?;
 
         let default_package_target = TomlPackageTarget {
@@ -642,8 +603,8 @@ mod test {
                 None,
             )
             .unwrap();
-        assert_eq!(manifest.value.package.name, "workspace-name");
-        assert_eq!(manifest.value.package.version.to_string(), "1.0.0");
+        assert_eq!(manifest.value.package.name.unwrap(), "workspace-name");
+        assert_eq!(manifest.value.package.version.unwrap().to_string(), "1.0.0");
         assert_eq!(
             manifest.value.package.description,
             Some("Package description".to_string())
@@ -667,29 +628,6 @@ mod test {
         );
     }
 
-    #[test]
-    fn test_missing_name_no_inheritance() {
-        let input = r#"
-        version = "1.0.0"
-
-        [build]
-        backend = { name = "bla", version = "1.0" }
-        "#;
-
-        let package = TomlPackage::from_toml_str(input).unwrap();
-        let workspace = WorkspacePackageProperties::default();
-
-        let parse_error = package
-            .into_manifest(
-                workspace,
-                PackageDefaults::default(),
-                &Preview::default(),
-                None,
-            )
-            .unwrap_err();
-        assert_snapshot!(format_parse_error(input, parse_error));
-    }
-
     #[test]
     fn test_mixed_inheritance_and_direct_values() {
         let input = r#"
@@ -719,8 +657,8 @@ mod test {
                 None,
             )
             .unwrap();
-        assert_eq!(manifest.value.package.name, "workspace-name");
-        assert_eq!(manifest.value.package.version.to_string(), "2.0.0");
+        assert_eq!(manifest.value.package.name.unwrap(), "workspace-name");
+        assert_eq!(manifest.value.package.version.unwrap().to_string(), "2.0.0");
         assert_eq!(
             manifest.value.package.description,
             Some("Workspace description".to_string())
@@ -810,8 +748,8 @@ mod test {
             .into_manifest(workspace, package_defaults, &Preview::default(), None)
             .unwrap();
         // Should use package defaults for name and version
-        assert_eq!(manifest.value.package.name, "default-name");
-        assert_eq!(manifest.value.package.version.to_string(), "2.0.0");
+        assert_eq!(manifest.value.package.name.unwrap(), "default-name");
+        assert_eq!(manifest.value.package.version.unwrap().to_string(), "2.0.0");
         // Should use direct value for description
         assert_eq!(
             manifest.value.package.description,
@@ -851,8 +789,8 @@ mod test {
             .into_manifest(workspace, package_defaults, &Preview::default(), None)
             .unwrap();
         // Should use workspace values for name and version (overrides defaults)
-        assert_eq!(manifest.value.package.name, "workspace-name");
-        assert_eq!(manifest.value.package.version.to_string(), "3.0.0");
+        assert_eq!(manifest.value.package.name.unwrap(), "workspace-name");
+        assert_eq!(manifest.value.package.version.unwrap().to_string(), "3.0.0");
         // Should use package defaults for description (not specified anywhere else)
         assert_eq!(
             manifest.value.package.description,
@@ -860,25 +798,6 @@ mod test {
         );
     }
 
-    #[test]
-    fn test_missing_required_field_no_defaults_no_workspace() {
-        let input = r#"
-        version = "1.0.0"
-
-        [build]
-        backend = { name = "bla", version = "1.0" }
-        "#;
-
-        let package = TomlPackage::from_toml_str(input).unwrap();
-        let workspace = WorkspacePackageProperties::default(); // Empty workspace
-        let package_defaults = PackageDefaults::default(); // Empty defaults
-
-        let parse_error = package
-            .into_manifest(workspace, package_defaults, &Preview::default(), None)
-            .unwrap_err();
-        assert_snapshot!(format_parse_error(input, parse_error));
-    }
-
     #[test]
     fn test_optional_workspace_inheritance_missing_workspace_value() {
         let input = r#"
diff --git a/crates/pixi_spec/src/lib.rs b/crates/pixi_spec/src/lib.rs
index 50480d6023..bb0b30752d 100644
--- a/crates/pixi_spec/src/lib.rs
+++ b/crates/pixi_spec/src/lib.rs
@@ -48,6 +48,10 @@ pub enum SpecConversionError {
     /// Encountered an invalid channel url or path
     #[error("the channel '{0}' could not be resolved")]
     InvalidChannel(String, #[source] ParseChannelError),
+
+    /// The `name` field is missing in the spec.
+    #[error("the `package.name` must be provided in versions of pixi-build-api-version <2")]
+    MissingName,
 }
 
 /// A package specification for pixi.
diff --git a/examples/pixi-build/array-api-extra/pixi.lock b/examples/pixi-build/array-api-extra/pixi.lock
index 1487d7b7f2..69953da686 100644
--- a/examples/pixi-build/array-api-extra/pixi.lock
+++ b/examples/pixi-build/array-api-extra/pixi.lock
@@ -125,7 +125,7 @@ packages:
   - python
   license: MIT
   input:
-    hash: cbfd3f78b3a0171befaa5d56f67f0c365b2ac9d7f0518fe7c080bd239fa6f59a
+    hash: 1101422a995a18b9c73ca5617a726f185782e5329c2739d754b921baaf16b7ca
     globs:
     - recipe.yaml
 - conda: https://prefix.dev/conda-forge/linux-64/bzip2-1.0.8-h4bc722e_7.conda
diff --git a/examples/pixi-build/cpp-sdl/pixi.lock b/examples/pixi-build/cpp-sdl/pixi.lock
index 8d6e739c87..9d6da7fedf 100644
--- a/examples/pixi-build/cpp-sdl/pixi.lock
+++ b/examples/pixi-build/cpp-sdl/pixi.lock
@@ -111,7 +111,7 @@ environments:
       - conda: https://prefix.dev/conda-forge/win-64/vc14_runtime-14.44.35208-h818238b_31.conda
       - conda: https://prefix.dev/conda-forge/win-64/vcomp14-14.44.35208-h818238b_31.conda
       - conda: .
-        build: h9352c13_0
+        subdir: win-64
 packages:
 - conda: https://prefix.dev/conda-forge/linux-64/_libgcc_mutex-0.1-conda_forge.tar.bz2
   sha256: fe51de6107f9edc7aa4f786a70f4a883943bc9d39b3bb7307c04c41410990726
@@ -1031,49 +1031,49 @@ packages:
 - conda: .
   name: sdl_example
   version: 0.1.0
-  build: h9352c13_0
-  subdir: win-64
+  build: hbf21a9e_0
+  subdir: linux-64
   depends:
-  - vc >=14.2,<15
-  - vc14_runtime >=14.29.30139
-  - ucrt >=10.0.20348.0
+  - libstdcxx >=15
+  - libgcc >=15
   - sdl2 >=2.32.54,<3.0a0
   input:
-    hash: 31ce6534707ac3b31b85d64591e46cb491b3da9ce64fcc66e64b8952d8d810f2
+    hash: edfac7bd3233d95d1173e54bb2b8900757a662b8a553d89225c1a81ea98796af
     globs: []
 - conda: .
   name: sdl_example
   version: 0.1.0
   build: hbf21a9e_0
-  subdir: linux-64
+  subdir: osx-64
   depends:
-  - libstdcxx >=15
-  - libgcc >=15
+  - libcxx >=20
   - sdl2 >=2.32.54,<3.0a0
   input:
-    hash: 31ce6534707ac3b31b85d64591e46cb491b3da9ce64fcc66e64b8952d8d810f2
+    hash: edfac7bd3233d95d1173e54bb2b8900757a662b8a553d89225c1a81ea98796af
     globs: []
 - conda: .
   name: sdl_example
   version: 0.1.0
   build: hbf21a9e_0
-  subdir: osx-64
+  subdir: osx-arm64
   depends:
   - libcxx >=20
   - sdl2 >=2.32.54,<3.0a0
   input:
-    hash: 31ce6534707ac3b31b85d64591e46cb491b3da9ce64fcc66e64b8952d8d810f2
+    hash: edfac7bd3233d95d1173e54bb2b8900757a662b8a553d89225c1a81ea98796af
     globs: []
 - conda: .
   name: sdl_example
   version: 0.1.0
   build: hbf21a9e_0
-  subdir: osx-arm64
+  subdir: win-64
   depends:
-  - libcxx >=20
+  - vc >=14.2,<15
+  - vc14_runtime >=14.29.30139
+  - ucrt >=10.0.20348.0
   - sdl2 >=2.32.54,<3.0a0
   input:
-    hash: 31ce6534707ac3b31b85d64591e46cb491b3da9ce64fcc66e64b8952d8d810f2
+    hash: edfac7bd3233d95d1173e54bb2b8900757a662b8a553d89225c1a81ea98796af
     globs: []
 - conda: https://prefix.dev/conda-forge/win-64/ucrt-10.0.22621.0-h57928b3_1.conda
   sha256: db8dead3dd30fb1a032737554ce91e2819b43496a0db09927edf01c32b577450
diff --git a/examples/pixi-build/recursive-run-dependencies/pixi.lock b/examples/pixi-build/recursive-run-dependencies/pixi.lock
index 9c6f1edf7e..a9e63899da 100644
--- a/examples/pixi-build/recursive-run-dependencies/pixi.lock
+++ b/examples/pixi-build/recursive-run-dependencies/pixi.lock
@@ -154,7 +154,7 @@ packages:
   - boltons
   - python
   input:
-    hash: 63bd47ad782aa0bd359bb4b735616e17f2f859ec603f845aba29cf04fd7b1120
+    hash: c33f206dfc06551f0242c7037fe4d8f019bf8fbb3473b626f808d8947b8671f7
     globs: []
 - conda: https://prefix.dev/conda-forge/linux-64/ld_impl_linux-64-2.43-h712a8e2_4.conda
   sha256: db73f38155d901a610b2320525b9dd3b31e4949215c870685fd92ea61b5ce472
@@ -564,7 +564,7 @@ packages:
   - depend
   - python
   input:
-    hash: fa14d594a1a54f7dc413f2cc4d5f3e072d961439d8390695b40fb4c36291fa4a
+    hash: d74786cfcf078d97d1c9d5e38440e52418fc4650ee65f4adc27d02afcf50c8d0
     globs: []
   sources:
     depend:
diff --git a/tests/data/satisfiability/source-dependency/pixi.lock b/tests/data/satisfiability/source-dependency/pixi.lock
index 5450d956b2..1d6a13065a 100644
--- a/tests/data/satisfiability/source-dependency/pixi.lock
+++ b/tests/data/satisfiability/source-dependency/pixi.lock
@@ -41,7 +41,7 @@ packages:
   - libstdcxx >=15
   - libgcc >=15
   input:
-    hash: 64a8e9eb88c4f6e944a37279a38a47fe7872454fb62bcafad63d200aef4b4a05
+    hash: 25e63e74a216901367b58ef438098792c9516ebd940e2f07d870b38ac24d470e
     globs: []
 - conda: https://prefix.dev/conda-forge/linux-64/libgcc-15.1.0-h767d61c_2.conda
   sha256: 0024f9ab34c09629621aefd8603ef77bf9d708129b0dd79029e502c39ffc2195
diff --git a/tests/data/workspace-discovery/split_package/bad/package/pixi.toml b/tests/data/workspace-discovery/split_package/bad/package/pixi.toml
deleted file mode 100644
index 5013a7eb4b..0000000000
--- a/tests/data/workspace-discovery/split_package/bad/package/pixi.toml
+++ /dev/null
@@ -1,8 +0,0 @@
-# This file should error because the workspace doesnt define a name.
-# [package]
-# name = "test_build_conda_package"
-# version = "1.0.0"
-
-[package.build.backend]
-name = "pixi-build-rattler-build"
-version = "0.1.*"
diff --git a/tests/data/workspace-discovery/split_package/bad/pixi.toml b/tests/data/workspace-discovery/split_package/bad/pixi.toml
deleted file mode 100644
index 81ff8d65ea..0000000000
--- a/tests/data/workspace-discovery/split_package/bad/pixi.toml
+++ /dev/null
@@ -1,12 +0,0 @@
-[workspace]
-channels = [
-  "https://prefix.dev/pixi-build-backends",
-  "https://prefix.dev/conda-forge",
-]
-platforms = ["linux-64"]
-preview = ["pixi-build"]
-# name = "test_build_conda_package"
-version = "1.0.0"
-
-[dependencies.test_build_conda_package]
-path = "package"