Troubleshooting guide for common issues
This article provides troubleshooting guidance for some of the common issues that customers might encounter. Listed errors are available to check when you turn on
live trace tool or collect from Azure Monitor.
404 from HttpHandlerUnexpectedResponse
Sending message during operation hub:<your-hub>,event:connect,type:sys,category:connections,requestType:Connect got unexpected response with status code 404.
This error indicates the event is registered in Web PubSub settings but fail to get a response from registered upstream URL.
- Check your upstream server function or method whether it's good to work.
- Check whether this event is intended to register. If not, remove it from the hub settings in Web PubSub side.
500 from HttpHandlerUnexpectedResponse
Sending message during operation handshake got unexpected response with status code 500. Detail: Get error from upstream: 'Request is denied as target server is invalid'
Sending message during operation hub:<your-hub>,event:connect,type:sys,category:connections,requestType:Connect got unexpected response with status code 500.
This error indicates event request get a
500 response from registered upstream.
- Check upstream side logs to investigate if there's some errors during handling the reported event.
Abuse protection for 'https://<upstream-host>/<upstream-path>' missing allowed origins: .
Web PubSub follows the CloudEvents Abuse Protection to validate the upstream webhook. Every registered upstream webhook URL will be validated. The
WebHook-Request-Origin request header is set to the service domain name
<web-pubsub-name>.webpubsub.azure.com, and it expects the response to have a header
WebHook-Allowed-Origin to contain this domain name or
Review the upstream side code to ensure when upstream receives the
OPTIONS preflight request from Web PubSub service, it's correctly handled following the rule that contains the expected header
WebHook-Allowed-Origin and value.
Besides, you can update to convenience server SDK, which automatically handles
Abuse Protection for you.
401 Unauthorized from AbuseProtectionResponseInvalidStatusCode
Abuse protection for 'https://<upstream-host>/<upstream-path>' failed: 401.
This error indicates the
Abuse Protection request get a
401 response from the registered upstream URL. For more information, see
- Check if there's any authentication enabled in upstream side, for example, the
App Keysfor a
WebPubSubTriggerAzure Function is set correctly, see example.
- Check upstream side logs to investigate how is the
Abuse Protectionrequest processed.
Client connection drops
When the client is connected to Azure Web PubSub, the persistent connection between the client and Azure Web PubSub can sometimes drop for different reasons. This section describes several possibilities causing such connection drop and provides some guidance on how to identify the root cause.
You can check the metric
Connection Close Count from Azure portal.
Possible reasons and root cause
|Normal||Close by clients|
|ClosedByAppServer||Close by server triggered Rest API call like
|ServiceReload||Close by service due to regular maintenance or backend auto scales|
|PingTimeout||Close by service due to client status unhealthy that service doesn't receive any regular pings|
|SlowClient||Close by service due to clients are not able to receive buffered messages fast enough|
SlowClient indicates that you have some clients not able to afford current traffic load. It's suggested to control the message sending speed and investigate client traces if client side performance can be improved.
Web PubSub different tiers have a hard limit on concurrent connection. This error indicates your traffic is beyond the supported connection count. For more information about pricing, see Web PubSub pricing.
Scale up to a paid tier(Standard or Premium) to have at least 1000 connections or scale out to more units that support more connections.