diff --git a/src/bun.js/webcore/S3Client.zig b/src/bun.js/webcore/S3Client.zig
index 941b8afec671..cb75e5433a62 100644
--- a/src/bun.js/webcore/S3Client.zig
+++ b/src/bun.js/webcore/S3Client.zig
@@ -151,12 +151,39 @@ pub const S3Client = struct {
             }
             return globalThis.throwInvalidArguments("Expected a path to presign", .{});
         };
-        errdefer path.deinit();
+        defer 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);
-        defer blob.detach();
-        return S3File.getPresignUrlFrom(&blob, globalThis, options);
+
+        // Compute credentials and sign the request directly without
+        // constructing a temporary blob. Creating and then cleaning up
+        // a blob store while an error is being thrown from signRequest
+        // corrupts the exception scope chain and crashes during GC.
+        //
+        // Match getPresignUrlFrom behavior: acl/storage_class are only
+        // used as defaults when extra options are provided (the old code
+        // only called s3.getCredentialsWithOptions when extra_options
+        // was non-null). Without options, they default to null.
+        const has_options = options != null and options.?.isObject();
+        var aws_options = try S3Credentials.getCredentialsWithOptions(
+            ptr.credentials.*,
+            ptr.options,
+            options,
+            if (has_options) ptr.acl else null,
+            if (has_options) ptr.storage_class else null,
+            ptr.request_payer,
+            globalThis,
+        );
+        defer aws_options.deinit();
+
+        // Normalize the path the same way Store.S3.path() does:
+        // URL.parse().s3Path(), strip trailing backslash, strip leading slash.
+        var s3_path = bun.URL.parse(path.slice()).s3Path();
+        if (s3_path.len > 0 and s3_path[s3_path.len - 1] == '\\')
+            s3_path = s3_path[0 .. s3_path.len - 1];
+        if (s3_path.len > 0 and (s3_path[0] == '/' or s3_path[0] == '\\'))
+            s3_path = s3_path[1..];
+        return S3File.presignFromCredentials(globalThis, s3_path, options, &aws_options);
     }
 
     pub fn exists(ptr: *@This(), globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.JSError!JSValue {
diff --git a/src/bun.js/webcore/S3File.zig b/src/bun.js/webcore/S3File.zig
index 29d0524f7dba..7189484d5d90 100644
--- a/src/bun.js/webcore/S3File.zig
+++ b/src/bun.js/webcore/S3File.zig
@@ -67,7 +67,7 @@ pub fn presign(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.J
 
     // accept a path or a blob
     var path_or_blob = try PathOrBlob.fromJSNoCopy(globalThis, &args);
-    errdefer {
+    defer {
         if (path_or_blob == .path) {
             path_or_blob.path.deinit();
         }
@@ -83,9 +83,23 @@ pub fn presign(globalThis: *jsc.JSGlobalObject, callframe: *jsc.CallFrame) bun.J
                 return globalThis.throwInvalidArguments("Expected a S3 or path to presign", .{});
             }
             const options = args.nextEat();
-            var blob = try constructS3FileInternalStore(globalThis, path.path, options);
-            defer blob.deinit();
-            return try getPresignUrlFrom(&blob, globalThis, options);
+
+            // Compute credentials and sign directly without constructing
+            // a temporary blob. Creating and cleaning up a blob store
+            // while an error is being thrown from signRequest corrupts
+            // the exception scope chain and crashes during GC.
+            const existing_credentials = globalThis.bunVM().transpiler.env.getS3Credentials();
+            var aws_options = try S3.S3Credentials.getCredentialsWithOptions(existing_credentials, .{}, options, null, null, false, globalThis);
+            defer aws_options.deinit();
+
+            // Normalize the path the same way Store.S3.path() does:
+            // URL.parse().s3Path(), strip trailing backslash, strip leading slash.
+            var s3_path = bun.URL.parse(path.path.slice()).s3Path();
+            if (s3_path.len > 0 and s3_path[s3_path.len - 1] == '\\')
+                s3_path = s3_path[0 .. s3_path.len - 1];
+            if (s3_path.len > 0 and (s3_path[0] == '/' or s3_path[0] == '\\'))
+                s3_path = s3_path[1..];
+            return try presignFromCredentials(globalThis, s3_path, options, &aws_options);
         },
         .blob => return try getPresignUrlFrom(&path_or_blob.blob, globalThis, args.nextEat()),
     }
@@ -464,6 +478,44 @@ pub const S3BlobStatTask = struct {
     }
 };
 
+/// Compute a presigned URL from already-resolved credentials, without
+/// constructing a blob. Used by S3Client.presign and S3File.presign to
+/// avoid the interaction between deferred blob cleanup and error throwing
+/// from signRequest that corrupts the exception scope chain.
+pub fn presignFromCredentials(globalThis: *jsc.JSGlobalObject, request_path: []const u8, extra_options: ?JSValue, credentialsWithOptions: *S3.S3CredentialsWithOptions) bun.JSError!JSValue {
+    var method: bun.http.Method = .GET;
+    var expires: usize = 86400;
+
+    if (extra_options) |options| {
+        if (options.isObject()) {
+            if (try options.getTruthyComptime(globalThis, "method")) |method_| {
+                method = try Method.fromJS(globalThis, method_) orelse {
+                    return globalThis.throwInvalidArguments("method must be GET, PUT, DELETE or HEAD when using s3 protocol", .{});
+                };
+            }
+            if (try options.getOptional(globalThis, "expiresIn", i32)) |expires_| {
+                if (expires_ <= 0) return globalThis.throwInvalidArguments("expiresIn must be greater than 0", .{});
+                expires = @intCast(expires_);
+            }
+        }
+    }
+
+    const result = credentialsWithOptions.credentials.signRequest(.{
+        .path = request_path,
+        .method = method,
+        .acl = credentialsWithOptions.acl,
+        .storage_class = credentialsWithOptions.storage_class,
+        .request_payer = credentialsWithOptions.request_payer,
+        .content_disposition = credentialsWithOptions.content_disposition,
+        .content_type = credentialsWithOptions.content_type,
+        .content_encoding = credentialsWithOptions.content_encoding,
+    }, false, .{ .expires = expires }) catch |sign_err| {
+        return S3.throwSignError(sign_err, globalThis);
+    };
+    defer result.deinit();
+    return bun.String.createUTF8ForJS(globalThis, result.url);
+}
+
 pub fn getPresignUrlFrom(this: *Blob, globalThis: *jsc.JSGlobalObject, extra_options: ?JSValue) bun.JSError!JSValue {
     if (!this.isS3()) {
         return globalThis.ERR(.INVALID_THIS, "presign is only possible for s3:// files", .{}).throw();
@@ -489,7 +541,7 @@ pub fn getPresignUrlFrom(this: *Blob, globalThis: *jsc.JSGlobalObject, extra_opt
                 };
             }
             if (try options.getOptional(globalThis, "expiresIn", i32)) |expires_| {
-                if (expires_ <= 0) return globalThis.throwInvalidArguments("expiresIn must be greather than 0", .{});
+                if (expires_ <= 0) return globalThis.throwInvalidArguments("expiresIn must be greater than 0", .{});
                 expires = @intCast(expires_);
             }
         }
@@ -505,6 +557,7 @@ pub fn getPresignUrlFrom(this: *Blob, globalThis: *jsc.JSGlobalObject, extra_opt
         .request_payer = credentialsWithOptions.request_payer,
         .content_disposition = credentialsWithOptions.content_disposition,
         .content_type = credentialsWithOptions.content_type,
+        .content_encoding = credentialsWithOptions.content_encoding,
     }, false, .{ .expires = expires }) catch |sign_err| {
         return S3.throwSignError(sign_err, globalThis);
     };
diff --git a/src/s3/credentials.zig b/src/s3/credentials.zig
index d6a8632611b7..7c25d8b34579 100644
--- a/src/s3/credentials.zig
+++ b/src/s3/credentials.zig
@@ -156,7 +156,7 @@ pub const S3Credentials = struct {
                                 new_credentials.changed_credentials = true;
                             }
                         } else {
-                            return globalObject.throwInvalidArgumentTypeValue("bucket", "string", js_value);
+                            return globalObject.throwInvalidArgumentTypeValue("sessionToken", "string", js_value);
                         }
                     }
                 }
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 000000000000..85de54ff498e
--- /dev/null
+++ b/test/js/bun/s3/s3-presign-missing-credentials.test.ts
@@ -0,0 +1,48 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe } from "harness";
+
+// Regression test: S3 presign with missing credentials should throw
+// ERR_S3_MISSING_CREDENTIALS instead of crashing.
+
+// Spawn subprocesses with S3 credential env vars explicitly unset so
+// the tests are not affected by ambient AWS credentials in the host.
+const cleanEnv = {
+  ...bunEnv,
+  AWS_ACCESS_KEY_ID: undefined,
+  AWS_SECRET_ACCESS_KEY: undefined,
+  S3_ACCESS_KEY_ID: undefined,
+  S3_SECRET_ACCESS_KEY: undefined,
+  AWS_SESSION_TOKEN: undefined,
+  S3_SESSION_TOKEN: undefined,
+  S3_ENDPOINT: undefined,
+  S3_BUCKET: undefined,
+  S3_REGION: undefined,
+  AWS_ENDPOINT: undefined,
+  AWS_BUCKET: undefined,
+  AWS_REGION: undefined,
+};
+
+test("S3 presign with missing credentials throws instead of crashing", async () => {
+  await using proc = Bun.spawn({
+    cmd: [
+      bunExe(),
+      "-e",
+      `
+      try { Bun.s3.presign("test-path"); } catch(e) { console.log(e.code); }
+      try { new Bun.S3Client().presign("test-path"); } catch(e) { console.log(e.code); }
+      try { Bun.S3Client.presign("test-path"); } catch(e) { console.log(e.code); }
+      Bun.gc(true);
+      console.log("ok");
+    `,
+    ],
+    env: cleanEnv,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stderr).not.toContain("error:");
+  expect(stdout.trim()).toBe("ERR_S3_MISSING_CREDENTIALS\nERR_S3_MISSING_CREDENTIALS\nERR_S3_MISSING_CREDENTIALS\nok");
+  expect(exitCode).toBe(0);
+});