diff --git a/codex-rs/app-server/README.md b/codex-rs/app-server/README.md
index a4f75d1541..1cd7f6c5d5 100644
--- a/codex-rs/app-server/README.md
+++ b/codex-rs/app-server/README.md
@@ -1930,7 +1930,7 @@ Codex supports these authentication modes. The current mode is surfaced in `acco
 - `account/login/start` — begin login (`apiKey`, `chatgpt`, `chatgptDeviceCode`, `amazonBedrock`).
 - `account/login/completed` (notify) — emitted when a login attempt finishes (success or error).
 - `account/login/cancel` — cancel a pending managed ChatGPT login by `loginId`.
-- `account/logout` — sign out; triggers `account/updated`.
+- `account/logout` — sign out; triggers `account/updated` on success.
 - `account/updated` (notify) — emitted whenever auth mode changes (`authMode`: `apikey`, `bedrockApiKey`, `chatgpt`, `personalAccessToken`, or `null`) and includes the current ChatGPT `planType` when available.
 - `account/rateLimits/read` — fetch ChatGPT rate limits, an optional effective monthly credit limit, and the earned rate-limit resets currently available, including expiry details when provided by the backend. Rate-limit updates arrive via `account/rateLimits/updated` (notify); reset-credit data is snapshot-only.
 - `account/rateLimitResetCredit/consume` — consume one earned reset using a caller-provided idempotency key, optionally selecting a reset-credit ID returned by `account/rateLimits/read`.
@@ -2060,7 +2060,7 @@ Codex stores the key and region as the primary Codex auth, replacing any previou
 { "method": "account/updated", "params": { "authMode": null, "planType": null } }
 ```
 
-When Codex-managed Amazon Bedrock auth is stored, logout removes that credential and clears the user-level `model_provider` only when it is still `"amazon-bedrock"`. A concurrent user config change is preserved. For AWS-managed Bedrock auth, logout is a no-op because the AWS SDK credential chain is managed outside Codex.
+When Codex-managed Amazon Bedrock auth is stored, logout removes that credential and clears the user-level `model_provider` only when it is still `"amazon-bedrock"`. A concurrent user config change is preserved. When Amazon Bedrock uses AWS-managed credentials, logout returns an error because the AWS SDK credential chain is managed outside Codex. Manage those credentials through AWS, or switch model providers before logging out Codex authentication.
 
 ### 7) Rate limits (ChatGPT)
 
diff --git a/codex-rs/app-server/src/request_processors/account_processor.rs b/codex-rs/app-server/src/request_processors/account_processor.rs
index 79d077750e..a598542247 100644
--- a/codex-rs/app-server/src/request_processors/account_processor.rs
+++ b/codex-rs/app-server/src/request_processors/account_processor.rs
@@ -833,26 +833,23 @@ impl AccountRequestProcessor {
     }
 
     async fn logout_common(&self) -> std::result::Result<Option<AuthMode>, JSONRPCErrorError> {
-        // Cancel any active login attempt.
-        {
-            let mut guard = self.active_login.lock().await;
-            if let Some(active) = guard.take() {
-                drop(active);
-            }
-        }
-
         let managed_bedrock_auth = matches!(
             self.auth_manager.auth_cached(),
             Some(CodexAuth::BedrockApiKey(_))
         );
         let config = self.load_latest_config().await;
         if config.model_provider.is_amazon_bedrock() && !managed_bedrock_auth {
-            return Ok(self
-                .auth_manager
-                .auth_cached()
-                .as_ref()
-                .map(CodexAuth::api_auth_mode)
-                .map(auth_mode_to_api));
+            return Err(invalid_request(
+                "cannot log out while Amazon Bedrock is using AWS-managed credentials; manage those credentials through AWS or switch model providers before logging out Codex authentication",
+            ));
+        }
+
+        // Cancel any active login attempt.
+        {
+            let mut guard = self.active_login.lock().await;
+            if let Some(active) = guard.take() {
+                drop(active);
+            }
         }
 
         match self.auth_manager.logout_with_revoke().await {
diff --git a/codex-rs/app-server/tests/suite/v2/account.rs b/codex-rs/app-server/tests/suite/v2/account.rs
index 909f099825..09a2bf7d95 100644
--- a/codex-rs/app-server/tests/suite/v2/account.rs
+++ b/codex-rs/app-server/tests/suite/v2/account.rs
@@ -1387,7 +1387,7 @@ async fn logout_managed_bedrock_restores_default_account() -> Result<()> {
 }
 
 #[tokio::test]
-async fn logout_aws_managed_bedrock_preserves_openai_auth_and_config() -> Result<()> {
+async fn logout_aws_managed_bedrock_errors_without_changing_auth_or_config() -> Result<()> {
     let codex_home = TempDir::new()?;
     create_config_toml(codex_home.path(), aws_managed_bedrock_config())?;
     login_with_api_key(
@@ -1407,18 +1407,18 @@ async fn logout_aws_managed_bedrock_preserves_openai_auth_and_config() -> Result
         .await?;
     timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
     let request_id = mcp.send_logout_account_request().await?;
-    let response = timeout(
+    let error = timeout(
         DEFAULT_READ_TIMEOUT,
-        mcp.read_stream_until_response_message(RequestId::Integer(request_id)),
+        mcp.read_stream_until_error_message(RequestId::Integer(request_id)),
     )
     .await??;
+    assert_eq!(error.error.code, -32600);
     assert_eq!(
-        to_response::<LogoutAccountResponse>(response)?,
-        LogoutAccountResponse {}
+        error.error.message,
+        "cannot log out while Amazon Bedrock is using AWS-managed credentials; manage those credentials through AWS or switch model providers before logging out Codex authentication"
     );
     assert_eq!(load_file_auth(codex_home.path())?, expected_auth);
     assert_eq!(read_config_toml(codex_home.path())?, expected_config);
-    assert_account_updated(&mut mcp, Some(AuthMode::ApiKey)).await?;
     Ok(())
 }