Instances of App Service hanging and unable to reset

Question

Instances of App Service hanging and unable to reset

Rob Houweling 21

The past few weeks I am experiencing a lot of issues with hanging Azure App instances and being unable to reset them. They had to be replaced on multiple occassions. But I want to know why this is happening. The application itself hasn't changed in over a long time and the issues only seem to increase. Traffic has also not increased for as far as I can tell.

Golla Venkata Pavani 7,535 Reputation points Microsoft External Staff Moderator

2026-05-29T11:22:42.2533333+00:00
Hi @Rob Houweling

I understand, unchanged code and stable usage, yet issues started suddenly. This is common on Small tier instances due to gradual memory/CPU pressure building up over time, which then triggers Azure’s proactive healing and retry storms on SignalR.

The high request spikes are mostly client retries on SignalR endpoints (/signalr/connect, etc.) when connections get unstable. Azure Service Bus doesn’t directly cause the 400 errors, but background processing can add resource contention.

Recommended Actions

Scale Up Immediately Even with the other apps stopped, upgrading from Small to Medium (or P1v2) usually resolves these symptoms quickly by giving the app more resources. Troubleshoot high CPU on Azure App Service

Improve SignalR Client Resilience Implement better backoff/retry logic on the client side to prevent retry storms. Azure SignalR Service Troubleshooting – 400 Bad Request

Kindly let us know if the above helps or you need further assistance on this issue.

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Golla Venkata Pavani 7,535 Reputation points Microsoft External Staff Moderator

2026-05-29T11:22:42.2533333+00:00

Hi @Rob Houweling

I understand, unchanged code and stable usage, yet issues started suddenly. This is common on Small tier instances due to gradual memory/CPU pressure building up over time, which then triggers Azure’s proactive healing and retry storms on SignalR.

The high request spikes are mostly client retries on SignalR endpoints (/signalr/connect, etc.) when connections get unstable. Azure Service Bus doesn’t directly cause the 400 errors, but background processing can add resource contention.

Recommended Actions

Scale Up Immediately Even with the other apps stopped, upgrading from Small to Medium (or P1v2) usually resolves these symptoms quickly by giving the app more resources. Troubleshoot high CPU on Azure App Service

Improve SignalR Client Resilience Implement better backoff/retry logic on the client side to prevent retry storms. Azure SignalR Service Troubleshooting – 400 Bad Request

Kindly let us know if the above helps or you need further assistance on this issue.

Please "upvote" if the information helped you. This will help us and others in the community as well.

Answer 1

Hi @Rob Houweling

Thank you for reaching us regarding the issue.

I understand, unchanged code and stable usage, yet issues started suddenly. This is common on Small tier instances due to gradual memory/CPU pressure building up over time, which then triggers Azure’s proactive healing and retry storms on SignalR.

The high request spikes are mostly client retries on SignalR endpoints (/signalr/connect, etc.) when connections get unstable. Azure Service Bus doesn’t directly cause the 400 errors, but background processing can add resource contention.

Recommended Actions

Scale Up Immediately Even with the other apps stopped, upgrading from Small to Medium (or P1v2) usually resolves these symptoms quickly by giving the app more resources. Troubleshoot high CPU on Azure App Service

Improve SignalR Client Resilience Implement better backoff/retry logic on the client side to prevent retry storms. Azure SignalR Service Troubleshooting – 400 Bad Request

Kindly let us know if the above helps or you need further assistance on this issue.

Please "accept" if the information helped you. This will help us and others in the community as well.