diff --git a/src/runtime/webcore/S3Client.zig b/src/runtime/webcore/S3Client.zig
index 941b8afec67..966db81d016 100644
--- a/src/runtime/webcore/S3Client.zig
+++ b/src/runtime/webcore/S3Client.zig
@@ -145,7 +145,7 @@ pub const S3Client = struct {
         const arguments = callframe.arguments_old(2).slice();
         var args = jsc.CallFrame.ArgumentsSlice.init(globalThis.bunVM(), arguments);
         defer args.deinit();
-        const path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
+        var path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
             if (args.len() == 0) {
                 return globalThis.ERR(.MISSING_ARGS, "Expected a path to presign", .{}).throw();
             }
@@ -155,6 +155,7 @@ pub const S3Client = struct {
 
         const options = args.nextEat();
         var blob = try S3File.constructS3FileWithS3CredentialsAndOptions(globalThis, path, options, ptr.credentials, ptr.options, ptr.acl, ptr.storage_class, ptr.request_payer);
+        path = .{ .string = bun.PathString.empty };
         defer blob.detach();
         return S3File.getPresignUrlFrom(&blob, globalThis, options);
     }
@@ -163,7 +164,7 @@ pub const S3Client = struct {
         const arguments = callframe.arguments_old(2).slice();
         var args = jsc.CallFrame.ArgumentsSlice.init(globalThis.bunVM(), arguments);
         defer args.deinit();
-        const path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
+        var path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
             if (args.len() == 0) {
                 return globalThis.ERR(.MISSING_ARGS, "Expected a path to check if it exists", .{}).throw();
             }
@@ -172,6 +173,7 @@ pub const S3Client = struct {
         errdefer path.deinit();
         const options = args.nextEat();
         var blob = try S3File.constructS3FileWithS3CredentialsAndOptions(globalThis, path, options, ptr.credentials, ptr.options, ptr.acl, ptr.storage_class, ptr.request_payer);
+        path = .{ .string = bun.PathString.empty };
         defer blob.detach();
         return S3File.S3BlobStatTask.exists(globalThis, &blob);
     }
@@ -180,7 +182,7 @@ pub const S3Client = struct {
         const arguments = callframe.arguments_old(2).slice();
         var args = jsc.CallFrame.ArgumentsSlice.init(globalThis.bunVM(), arguments);
         defer args.deinit();
-        const path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
+        var path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
             if (args.len() == 0) {
                 return globalThis.ERR(.MISSING_ARGS, "Expected a path to check the size of", .{}).throw();
             }
@@ -189,6 +191,7 @@ pub const S3Client = struct {
         errdefer path.deinit();
         const options = args.nextEat();
         var blob = try S3File.constructS3FileWithS3CredentialsAndOptions(globalThis, path, options, ptr.credentials, ptr.options, ptr.acl, ptr.storage_class, ptr.request_payer);
+        path = .{ .string = bun.PathString.empty };
         defer blob.detach();
         return S3File.S3BlobStatTask.size(globalThis, &blob);
     }
@@ -197,7 +200,7 @@ pub const S3Client = struct {
         const arguments = callframe.arguments_old(2).slice();
         var args = jsc.CallFrame.ArgumentsSlice.init(globalThis.bunVM(), arguments);
         defer args.deinit();
-        const path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
+        var path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
             if (args.len() == 0) {
                 return globalThis.ERR(.MISSING_ARGS, "Expected a path to check the stat of", .{}).throw();
             }
@@ -206,6 +209,7 @@ pub const S3Client = struct {
         errdefer path.deinit();
         const options = args.nextEat();
         var blob = try S3File.constructS3FileWithS3CredentialsAndOptions(globalThis, path, options, ptr.credentials, ptr.options, ptr.acl, ptr.storage_class, ptr.request_payer);
+        path = .{ .string = bun.PathString.empty };
         defer blob.detach();
         return S3File.S3BlobStatTask.stat(globalThis, &blob);
     }
@@ -214,7 +218,7 @@ pub const S3Client = struct {
         const arguments = callframe.arguments_old(3).slice();
         var args = jsc.CallFrame.ArgumentsSlice.init(globalThis.bunVM(), arguments);
         defer args.deinit();
-        const path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
+        var path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
             return globalThis.ERR(.MISSING_ARGS, "Expected a path to write to", .{}).throw();
         };
         errdefer path.deinit();
@@ -224,6 +228,7 @@ pub const S3Client = struct {
 
         const options = args.nextEat();
         var blob = try S3File.constructS3FileWithS3CredentialsAndOptions(globalThis, path, options, ptr.credentials, ptr.options, ptr.acl, ptr.storage_class, ptr.request_payer);
+        path = .{ .string = bun.PathString.empty };
         defer blob.detach();
         var blob_internal: PathOrBlob = .{ .blob = blob };
         return Blob.writeFileInternal(globalThis, &blob_internal, data, .{
@@ -248,12 +253,13 @@ pub const S3Client = struct {
         const arguments = callframe.arguments_old(2).slice();
         var args = jsc.CallFrame.ArgumentsSlice.init(globalThis.bunVM(), arguments);
         defer args.deinit();
-        const path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
+        var path: jsc.Node.PathLike = try jsc.Node.PathLike.fromJS(globalThis, &args) orelse {
             return globalThis.ERR(.MISSING_ARGS, "Expected a path to unlink", .{}).throw();
         };
         errdefer path.deinit();
         const options = args.nextEat();
         var blob = try S3File.constructS3FileWithS3CredentialsAndOptions(globalThis, path, options, ptr.credentials, ptr.options, ptr.acl, ptr.storage_class, ptr.request_payer);
+        path = .{ .string = bun.PathString.empty };
         defer blob.detach();
         return blob.store.?.data.s3.unlink(blob.store.?, globalThis, options);
     }
diff --git a/src/runtime/webcore/S3File.zig b/src/runtime/webcore/S3File.zig
index 41e900fb987..6feff4b0e7e 100644
--- a/src/runtime/webcore/S3File.zig
+++ b/src/runtime/webcore/S3File.zig
@@ -84,6 +84,7 @@ pub fn presign(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.J
             }
             const options = args.nextEat();
             var blob = try constructS3FileInternalStore(globalThis, path.path, options);
+            path_or_blob = .{ .path = .{ .path = .{ .string = bun.PathString.empty } } };
             defer blob.deinit();
             return try getPresignUrlFrom(&blob, globalThis, options);
         },
@@ -114,6 +115,7 @@ pub fn unlink(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.JS
             }
             const options = args.nextEat();
             var blob = try constructS3FileInternalStore(globalThis, path.path, options);
+            path_or_blob = .{ .path = .{ .path = .{ .string = bun.PathString.empty } } };
             defer blob.deinit();
             return try blob.store.?.data.s3.unlink(blob.store.?, globalThis, options);
         },
@@ -151,6 +153,7 @@ pub fn write(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.JSE
                 return globalThis.throwInvalidArguments("Expected a S3 or path to upload", .{});
             }
             var blob = try constructS3FileInternalStore(globalThis, path.path, options);
+            path_or_blob = .{ .path = .{ .path = .{ .string = bun.PathString.empty } } };
             defer blob.deinit();
 
             var blob_internal: PathOrBlob = .{ .blob = blob };
@@ -190,6 +193,7 @@ pub fn size(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.JSEr
                 return globalThis.throwInvalidArguments("Expected a S3 or path to get size", .{});
             }
             var blob = try constructS3FileInternalStore(globalThis, path.path, options);
+            path_or_blob = .{ .path = .{ .path = .{ .string = bun.PathString.empty } } };
             defer blob.deinit();
 
             return S3BlobStatTask.size(globalThis, &blob);
@@ -223,6 +227,7 @@ pub fn exists(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.JS
                 return globalThis.throwInvalidArguments("Expected a S3 or path to check if it exists", .{});
             }
             var blob = try constructS3FileInternalStore(globalThis, path.path, options);
+            path_or_blob = .{ .path = .{ .path = .{ .string = bun.PathString.empty } } };
             defer blob.deinit();
 
             return S3BlobStatTask.exists(globalThis, &blob);
@@ -256,6 +261,9 @@ pub fn constructS3FileWithS3CredentialsAndOptions(
     var aws_options = try S3.S3Credentials.getCredentialsWithOptions(default_credentials.*, default_options, options, default_acl, default_storage_class, default_request_payer, globalObject);
     defer aws_options.deinit();
 
+    // initS3 transfers ownership of `path` to the store. Nothing below may
+    // return an error: the caller's `errdefer path.deinit()` still aliases
+    // the same string the store now owns.
     const store = brk: {
         if (aws_options.changed_credentials) {
             break :brk bun.handleOom(Blob.Store.initS3(path, null, aws_options.credentials, bun.default_allocator));
@@ -263,38 +271,13 @@ pub fn constructS3FileWithS3CredentialsAndOptions(
             break :brk bun.handleOom(Blob.Store.initS3WithReferencedCredentials(path, null, default_credentials, bun.default_allocator));
         }
     };
-    errdefer store.deinit();
     store.data.s3.options = aws_options.options;
     store.data.s3.acl = aws_options.acl;
     store.data.s3.storage_class = aws_options.storage_class;
     store.data.s3.request_payer = aws_options.request_payer;
 
     var blob = Blob.initWithStore(store, globalObject);
-    if (options) |opts| {
-        if (opts.isObject()) {
-            if (try opts.getTruthyComptime(globalObject, "type")) |file_type| {
-                inner: {
-                    if (file_type.isString()) {
-                        var allocator = bun.default_allocator;
-                        var str = try file_type.toSlice(globalObject, bun.default_allocator);
-                        defer str.deinit();
-                        const slice = str.slice();
-                        if (!strings.isAllASCII(slice)) {
-                            break :inner;
-                        }
-                        blob.content_type_was_set = true;
-                        if (globalObject.bunVM().mimeType(str.slice())) |entry| {
-                            blob.content_type = entry.value;
-                            break :inner;
-                        }
-                        const content_type_buf = bun.handleOom(allocator.alloc(u8, slice.len));
-                        blob.content_type = strings.copyLowercase(slice, content_type_buf);
-                        blob.content_type_allocated = true;
-                    }
-                }
-            }
-        }
-    }
+    setBlobContentType(&blob, aws_options.content_type, globalObject);
     return blob;
 }
 
@@ -306,41 +289,33 @@ pub fn constructS3FileWithS3Credentials(
 ) bun.JSError!Blob {
     var aws_options = try S3.S3Credentials.getCredentialsWithOptions(existing_credentials, .{}, options, null, null, false, globalObject);
     defer aws_options.deinit();
+    // initS3 transfers ownership of `path` to the store. Nothing below may
+    // return an error: the caller's `errdefer path.deinit()` still aliases
+    // the same string the store now owns.
     const store = bun.handleOom(Blob.Store.initS3(path, null, aws_options.credentials, bun.default_allocator));
-    errdefer store.deinit();
     store.data.s3.options = aws_options.options;
     store.data.s3.acl = aws_options.acl;
     store.data.s3.storage_class = aws_options.storage_class;
     store.data.s3.request_payer = aws_options.request_payer;
 
     var blob = Blob.initWithStore(store, globalObject);
-    if (options) |opts| {
-        if (opts.isObject()) {
-            if (try opts.getTruthyComptime(globalObject, "type")) |file_type| {
-                inner: {
-                    if (file_type.isString()) {
-                        var allocator = bun.default_allocator;
-                        var str = try file_type.toSlice(globalObject, bun.default_allocator);
-                        defer str.deinit();
-                        const slice = str.slice();
-                        if (!strings.isAllASCII(slice)) {
-                            break :inner;
-                        }
-                        blob.content_type_was_set = true;
-                        if (globalObject.bunVM().mimeType(str.slice())) |entry| {
-                            blob.content_type = entry.value;
-                            break :inner;
-                        }
-                        const content_type_buf = bun.handleOom(allocator.alloc(u8, slice.len));
-                        blob.content_type = strings.copyLowercase(slice, content_type_buf);
-                        blob.content_type_allocated = true;
-                    }
-                }
-            }
-        }
-    }
+    setBlobContentType(&blob, aws_options.content_type, globalObject);
     return blob;
 }
+
+fn setBlobContentType(blob: *Blob, content_type: ?[]const u8, globalObject: *jsc.JSGlobalObject) void {
+    const slice = content_type orelse return;
+    if (!strings.isAllASCII(slice)) return;
+    blob.content_type_was_set = true;
+    if (globalObject.bunVM().mimeType(slice)) |entry| {
+        blob.content_type = entry.value;
+        return;
+    }
+    const content_type_buf = bun.handleOom(bun.default_allocator.alloc(u8, slice.len));
+    blob.content_type = strings.copyLowercase(slice, content_type_buf);
+    blob.content_type_allocated = true;
+}
+
 fn constructS3FileInternal(
     globalObject: *jsc.JSGlobalObject,
     path: jsc.Node.PathLike,
@@ -574,6 +549,7 @@ pub fn stat(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.JSEr
                 return globalThis.throwInvalidArguments("Expected a S3 or path to get size", .{});
             }
             var blob = try constructS3FileInternalStore(globalThis, path.path, options);
+            path_or_blob = .{ .path = .{ .path = .{ .string = bun.PathString.empty } } };
             defer blob.deinit();
 
             return S3BlobStatTask.stat(globalThis, &blob);
diff --git a/test/js/bun/s3/s3-presign-missing-credentials.test.ts b/test/js/bun/s3/s3-presign-missing-credentials.test.ts
new file mode 100644
index 00000000000..690e7739aa8
--- /dev/null
+++ b/test/js/bun/s3/s3-presign-missing-credentials.test.ts
@@ -0,0 +1,51 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe } from "harness";
+
+// The path string's ref is transferred to the blob store; when the operation
+// fails synchronously after that point the errdefer cleanup must not deref it
+// a second time.
+test("S3Client path methods throw instead of crashing on synchronous errors", async () => {
+  const env = { ...bunEnv };
+  for (const k of [
+    "S3_ACCESS_KEY_ID",
+    "S3_SECRET_ACCESS_KEY",
+    "S3_BUCKET",
+    "S3_ENDPOINT",
+    "S3_REGION",
+    "S3_SESSION_TOKEN",
+    "AWS_ACCESS_KEY_ID",
+    "AWS_SECRET_ACCESS_KEY",
+    "AWS_BUCKET",
+    "AWS_ENDPOINT",
+    "AWS_REGION",
+    "AWS_SESSION_TOKEN",
+  ]) {
+    delete env[k];
+  }
+
+  await using proc = Bun.spawn({
+    cmd: [
+      bunExe(),
+      "-e",
+      `
+        const out = [];
+        try { Bun.S3Client.presign("myfile"); } catch (e) { out.push(e.code); }
+        try { new Bun.S3Client({}).presign("myfile"); } catch (e) { out.push(e.code); }
+        try { Bun.S3Client.write("myfile", null); } catch (e) { out.push(e.code); }
+        try { new Bun.S3Client({}).write("myfile", null); } catch (e) { out.push(e.code); }
+        console.log(out.join(":"));
+      `,
+    ],
+    env,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stderr).toBe("");
+  expect(stdout.trim()).toBe(
+    "ERR_S3_MISSING_CREDENTIALS:ERR_S3_MISSING_CREDENTIALS:ERR_INVALID_ARG_TYPE:ERR_INVALID_ARG_TYPE",
+  );
+  expect(exitCode).toBe(0);
+});