Fix initialization race conditions and improve error resilience.

- `getServerByName` now propagates errors from the internal `set-name` request instead of silently swallowing them.
- `onStart` failures no longer permanently brick the Durable Object. Errors are caught inside `blockConcurrencyWhile` (preserving the input gate) and the status is reset, allowing subsequent requests to retry initialization.
- `fetch()` now retries initialization when a previous `onStart` attempt failed, instead of skipping it because the name was already set.
- Errors in `fetch()` (including `onStart` failures and malformed props) are now caught and returned as proper 500 responses instead of crashing as unhandled exceptions.
- WebSocket handlers (`webSocketMessage`, `webSocketClose`, `webSocketError`) are now wrapped in try/catch so that transient `onStart` failures don't kill the connection — the next message will retry.

Author: threepointone

.changeset/fix-initialization-race-conditions.md

@@ -0,0 +1,11 @@
+---
+"partyserver": patch
+---
+
+Fix initialization race conditions and improve error resilience.
+
+- `getServerByName` now propagates errors from the internal `set-name` request instead of silently swallowing them.
+- `onStart` failures no longer permanently brick the Durable Object. Errors are caught inside `blockConcurrencyWhile` (preserving the input gate) and the status is reset, allowing subsequent requests to retry initialization.
+- `fetch()` now retries initialization when a previous `onStart` attempt failed, instead of skipping it because the name was already set.
+- Errors in `fetch()` (including `onStart` failures and malformed props) are now caught and returned as proper 500 responses instead of crashing as unhandled exceptions.
+- WebSocket handlers (`webSocketMessage`, `webSocketClose`, `webSocketError`) are now wrapped in try/catch so that transient `onStart` failures don't kill the connection — the next message will retry.

package-lock.json

@@ -37,6 +37,6 @@
   "devDependencies": {
     "@cloudflare/workers-types": "^4.20251218.0",
     "hono": "^4.11.1",
-    "partyserver": "^0.1.3"
+    "partyserver": "^0.1.4"
   }
 }

packages/hono-party/package.json

@@ -19,7 +19,7 @@
   ],
   "dependencies": {
     "nanoid": "^5.1.6",
-    "partysocket": "^1.1.12"
+    "partysocket": "^1.1.13"
   },
   "scripts": {
     "build": "tsx scripts/build.ts"

packages/partyfn/package.json

@@ -67,13 +67,7 @@ export async function getServerByName<
   }
 
   // unfortunately we have to await this
-  await stub
-    .fetch(req)
-    // drain body
-    .then((res) => res.text())
-    .catch((e) => {
-      console.error("Could not set server name:", e);
-    });
+  await stub.fetch(req).then((res) => res.text());
 
   return stub;
 }
@@ -366,34 +360,32 @@ export class Server<
    * Handle incoming requests to the server.
    */
   async fetch(request: Request): Promise<Response> {
-    // Set the props in-mem if the request included them.
-    const props = request.headers.get("x-partykit-props");
-    if (props) {
-      try {
+    try {
+      // Set the props in-mem if the request included them.
+      const props = request.headers.get("x-partykit-props");
+      if (props) {
         this.#_props = JSON.parse(props);
-      } catch {
-        // This should never happen but log it just in case
-        console.error("Internal error parsing context props.");
       }
-    }
+      if (!this.#_name) {
+        // This is temporary while we solve https://github.com/cloudflare/workerd/issues/2240
 
-    if (!this.#_name) {
-      // This is temporary while we solve https://github.com/cloudflare/workerd/issues/2240
-
-      // get namespace and room from headers
-      // const namespace = request.headers.get("x-partykit-namespace");
-      const room = request.headers.get("x-partykit-room");
-      if (
-        // !namespace ||
-        !room
-      ) {
-        throw new Error(`Missing namespace or room headers when connecting to ${this.#ParentClass.name}.
+        // get namespace and room from headers
+        // const namespace = request.headers.get("x-partykit-namespace");
+        const room = request.headers.get("x-partykit-room");
+        if (
+          // !namespace ||
+          !room
+        ) {
+          throw new Error(`Missing namespace or room headers when connecting to ${this.#ParentClass.name}.
 Did you try connecting directly to this Durable Object? Try using getServerByName(namespace, id) instead.`);
+        }
+        await this.setName(room);
+      } else if (this.#status !== "started") {
+        // Name was set by a previous request but initialization failed.
+        // Retry initialization so the server can recover from transient
+        // onStart failures.
+        await this.#initialize();
       }
-      await this.setName(room);
-    }
-
-    try {
       const url = new URL(request.url);
 
       // TODO: this is a hack to set the server name,
@@ -450,7 +442,7 @@ Did you try connecting directly to this Durable Object? Try using getServerByNam
       }
     } catch (err) {
       console.error(
-        `Error in ${this.#ParentClass.name}:${this.name} fetch:`,
+        `Error in ${this.#ParentClass.name}:${this.#_name ?? "<unnamed>"} fetch:`,
         err
       );
       if (!(err instanceof Error)) throw err;
@@ -477,13 +469,20 @@ Did you try connecting directly to this Durable Object? Try using getServerByNam
       return;
     }
 
-    const connection = createLazyConnection(ws);
+    try {
+      const connection = createLazyConnection(ws);
 
-    // rehydrate the server name if it's woken up
-    await this.setName(connection.server);
-    // TODO: ^ this shouldn't be async
+      // rehydrate the server name if it's woken up
+      await this.setName(connection.server);
+      // TODO: ^ this shouldn't be async
 
-    return this.onMessage(connection, message);
+      return this.onMessage(connection, message);
+    } catch (e) {
+      console.error(
+        `Error in ${this.#ParentClass.name}:${this.#_name ?? "<unnamed>"} webSocketMessage:`,
+        e
+      );
+    }
   }
 
   async webSocketClose(
@@ -496,35 +495,58 @@ Did you try connecting directly to this Durable Object? Try using getServerByNam
       return;
     }
 
-    const connection = createLazyConnection(ws);
+    try {
+      const connection = createLazyConnection(ws);
 
-    // rehydrate the server name if it's woken up
-    await this.setName(connection.server);
-    // TODO: ^ this shouldn't be async
+      // rehydrate the server name if it's woken up
+      await this.setName(connection.server);
+      // TODO: ^ this shouldn't be async
 
-    return this.onClose(connection, code, reason, wasClean);
+      return this.onClose(connection, code, reason, wasClean);
+    } catch (e) {
+      console.error(
+        `Error in ${this.#ParentClass.name}:${this.#_name ?? "<unnamed>"} webSocketClose:`,
+        e
+      );
+    }
   }
 
   async webSocketError(ws: WebSocket, error: unknown): Promise<void> {
     if (!isPartyServerWebSocket(ws)) {
       return;
     }
 
-    const connection = createLazyConnection(ws);
+    try {
+      const connection = createLazyConnection(ws);
 
-    // rehydrate the server name if it's woken up
-    await this.setName(connection.server);
-    // TODO: ^ this shouldn't be async
+      // rehydrate the server name if it's woken up
+      await this.setName(connection.server);
+      // TODO: ^ this shouldn't be async
 
-    return this.onError(connection, error);
+      return this.onError(connection, error);
+    } catch (e) {
+      console.error(
+        `Error in ${this.#ParentClass.name}:${this.#_name ?? "<unnamed>"} webSocketError:`,
+        e
+      );
+    }
   }
 
   async #initialize(): Promise<void> {
+    let error: unknown;
     await this.ctx.blockConcurrencyWhile(async () => {
       this.#status = "starting";
-      await this.onStart(this.#_props);
-      this.#status = "started";
+      try {
+        await this.onStart(this.#_props);
+        this.#status = "started";
+      } catch (e) {
+        this.#status = "zero";
+        error = e;
+      }
     });
+    // Re-throw outside blockConcurrencyWhile so the DO's input gate
+    // isn't permanently broken, allowing subsequent requests to retry.
+    if (error) throw error;
   }
 
   #attachSocketEventHandlers(connection: Connection) {

packages/partyserver/src/index.ts

@@ -402,6 +402,86 @@ describe("Hibernating Server (setName handles initialization)", () => {
   });
 });
 
+describe("Error handling", () => {
+  it("returns 500 with useful message when room header is missing", async () => {
+    // Send a request directly to a DO stub without the x-partykit-room header.
+    // This should return a 500 with the "Missing namespace or room headers"
+    // message, NOT crash with "Attempting to read .name before it was set".
+    const id = env.Stateful.idFromName("no-header-test");
+    const stub = env.Stateful.get(id);
+    const response = await stub.fetch(
+      new Request("http://example.com/some-path")
+    );
+    expect(response.status).toBe(500);
+    const body = await response.text();
+    expect(body).toContain("Missing namespace or room headers");
+  });
+});
+
+describe("onStart failure recovery", () => {
+  it("resets status so subsequent requests can retry initialization", async () => {
+    const ctx = createExecutionContext();
+
+    // First request: onStart throws on first attempt, returns 500
+    const request1 = new Request(
+      "http://example.com/parties/failing-on-start-server/recovery-test"
+    );
+    const response1 = await worker.fetch(request1, env, ctx);
+    expect(response1.status).toBe(500);
+
+    // Second request: onStart should succeed on the retry because
+    // the status was reset to "zero" (not stuck at "starting"), and
+    // the error was caught inside blockConcurrencyWhile so the DO's
+    // input gate wasn't permanently broken.
+    const request2 = new Request(
+      "http://example.com/parties/failing-on-start-server/recovery-test"
+    );
+    const response2 = await worker.fetch(request2, env, ctx);
+    expect(response2.status).toBe(200);
+    const data = (await response2.json()) as {
+      counter: number;
+      failCount: number;
+    };
+    // counter is 2 because onStart ran twice (first failed, second succeeded)
+    expect(data.counter).toEqual(2);
+    expect(data.failCount).toEqual(1);
+  });
+});
+
+describe("Hibernating server name rehydration", () => {
+  it("this.name is available in onMessage after wake-up", async () => {
+    const ctx = createExecutionContext();
+    const request = new Request(
+      "http://example.com/parties/hibernating-name-in-message/rehydrate-test",
+      {
+        headers: { Upgrade: "websocket" }
+      }
+    );
+    const response = await worker.fetch(request, env, ctx);
+    const ws = response.webSocket!;
+    ws.accept();
+
+    // Wait for the onConnect message which includes the name
+    const connectMessage = await new Promise<string>((resolve) => {
+      ws.addEventListener("message", (e) => resolve(e.data as string), {
+        once: true
+      });
+    });
+    expect(connectMessage).toEqual("connected:rehydrate-test");
+
+    // Send a message to trigger onMessage, which also reads this.name
+    ws.send("ping");
+    const nameMessage = await new Promise<string>((resolve) => {
+      ws.addEventListener("message", (e) => resolve(e.data as string), {
+        once: true
+      });
+    });
+    expect(nameMessage).toEqual("name:rehydrate-test");
+
+    ws.close();
+  });
+});
+
 describe("Alarm (initialize without redundant blockConcurrencyWhile)", () => {
   it("properly initializes on alarm and calls onAlarm", async () => {
     // Use a single stub for the entire test so runDurableObjectAlarm