Azure DevOps release pipeline failing with TF400893: Unable to contact the server

Hello Aniket Prasad,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

TF400893: Unable to contact the server means your pipeline agent temporarily lost connection to the Azure DevOps service or to Azure during task execution. This is a connectivity-related error - not necessarily a problem in your YAML or task configuration.

Sometimes Azure DevOps or Azure endpoints experience short outages. Re-run the pipeline most transient errors clear on retry.

Verify If the Azure CLI task uses a service connection, the token or credentials may have expired or lost permissions.

If the task was running long , it might have exceeded the agent timeout or network idle limit. Add retry logic or split large scripts into smaller steps.

Azure DevOps enforces rate limits. If many parallel builds or releases are running, you might hit throttling temporarily. Space out pipeline runs.

• Troubleshoot Azure Resource Manager (ARM) service connections
• Debug deployment issues
• Azure DevOps Service Status
• Azure Service Fabric deployment tutorial

Please provide the below details if still issue persists.

• Have you noticed any specific pattern or time when this issue occurs?
• Are there any other errors in the logs leading up to the TF400893 message?

Please let me know if you have any further question.

Thanks

Hello Aniket Prasad,

Following up to see if the above provided answer was helpful. If it answers your query, please do upvote. If you have any further queries, do let us know.

Thanks

Hello Rupesh Asati,

We are observing failures behaviors in our Azure DevOps release pipelines. The affected stage is the Azure CLI task within our release pipeline(Deployment). This issue is impacting production releases and causing business disruption. Please review the details below and advise on an immediate resolution or provide an ETA.

Observed Behavior: Noticed this behavior on November 30th and 31st 2025
Screenshot 2025-11-02 141401.png

Initially - November 30–31, 2025

Triggered Pipelines initialize successfully and complete build and artifact download steps without issue.

In release pipeline, During the Azure CLI step, the process runs for approximately 60 minutes before failing with:
TF400893: Unable to contact the server. This is most likely caused by a network error.

The error occurs everytime, but once triggered, the task exits with ##[error]Script failed with exit code: 1 and the agent disconnects.

Prior steps in the release pipeline (AzCopy to Blob, AKS deployment preparation, etc.) complete successfully. No recent changes were made to the YAML, task configuration, or service connection.

Current update - Noticed this behavior on November 2 2025 The release pipelines are still falling but they don't persist for 60 mins is fails instantly and the following error was observed in the logs

ERROR: (BadRequest) All Changes to Azure Frontdoor Configuration are blocked currently. Code: BadRequest Message: All Changes to Azure Frontdoor Configuration are blocked currently. ##[error]Script failed with exit code: 1

**Unable to remove cache/ purge Azure frontdoor path '/*'
**

Please provide immediate solution and if not an ETA as we have important production releases casuing business loss

Azure DevOps Org Region: [East US ] Agent Type: Microsoft-hosted Release ID: 1521 Error Signature: TF400893

Hello @Aniket Prasad , following up to see if you had a chance to check my previous response in Private message and if it was helpful. Please do let me know if you're still facing the issue and need any further assistance on this.