Fixing the user container exec format error error
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Updated at December 17, 2025
Issue description
When attempting to start a container in Serverless Containers, you see the following error in its logs:
"errorMessage":"user container finished with error: fork/exec /usr/local/bin/python3: exec format error","errorType":"UserCodeError"}
Solution
We recommend building a container with the architecture explicitly set to --platform=linux/amd64.
For more information about the Serverless Containers runtime, see this article.
If the issue persists
If the above actions did not help, create a support ticket
- ID of your container in Serverless Containers.
- Full error message from the container execution log.