how to fix error 'subprocess.CalledProcessError: Command '['python', '-m', 'venv', './isolated_env']' returned non-zero exit status 1.'

Question

how to fix error 'subprocess.CalledProcessError: Command '['python', '-m', 'venv', './isolated_env']' returned non-zero exit status 1.'

Sahoo, Anasuya 20

Hi Team,

I am developing an application where it accepts any source code (COBOL, SAP ABAP, Java etc.) and convert that to Python and executes the converted Python code in isolated environment which should be dynamically created during run time. I have deployed the application using Azure App Service. But I am getting attached error while creating isolated environment. Kindly help.Azure Error2.JPG

Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-07T11:42:38.4866667+00:00

Hi Sahoo, Anasuya, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-08T19:54:30.8233333+00:00

Hi Sahoo, Anasuya, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Sahoo, Anasuya 20 Reputation points

2025-05-15T15:27:47.94+00:00

Thank you so much for your quick response. Sorry for the delay. Since dock container might take some time, I thought I can create isolated environment locally and take that to Azure and run the python code in that isolated environment. If the converted python code requires additional library, then only those will be installed during run time so that time will be saved. In that way also, I am getting error. I think it's timing out. But my code is working perfectly in isolated environment in local system. Please check my error and suggest. Thanks in Advance!
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-15T17:22:15.02+00:00

Hi Sahoo, Anasuya,
When you package and move your local isolated environment to azure and try to install an additional package on the runtime, the azure can still consider it as a "long -lasting operation". Combined with an overhead of network calls and subprocess execution, it can give rise to timeout errors - especially under /convert endpoints where you handle dynamic execution.

Instead of installing libraries on runtime, include all usually the required packages during the construction of your deployment. You can use a requirement.

If the dynamic library installation or conversion argument cannot be shortened, consider the Azure services designed for it:

Azure Container Apps- complete control over the environment and runtime, perfect for custom isolated environment.

Azure Durable Functions- ideal for long-run background jobs such as durable work-code conversion.

While the ideal is not long term, you can temporarily increase the timeout range via web.config or applicationhost.config, but this is a workaround - not a scalable solution.

If you look at the log's like an unknown language unknown, it can clearly be beneficial to delay or avoid abortion in passing language metadata or preprocessing signal.
Custom Container Deployment in App Service
Azure App Service Timeouts
if you have any further concerns or queries, please feel free to reach out to us.
Sahoo, Anasuya 20 Reputation points

2025-05-16T13:22:41.6633333+00:00

Thank you so much Alekhya for your suggestion. Let me try Azure Container Apps and get back to you.

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Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-07T11:42:38.4866667+00:00

Hi Sahoo, Anasuya, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-08T19:54:30.8233333+00:00

Hi Sahoo, Anasuya, We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Sahoo, Anasuya 20 Reputation points

2025-05-15T15:27:47.94+00:00

Thank you so much for your quick response. Sorry for the delay. Since dock container might take some time, I thought I can create isolated environment locally and take that to Azure and run the python code in that isolated environment. If the converted python code requires additional library, then only those will be installed during run time so that time will be saved. In that way also, I am getting error. I think it's timing out. But my code is working perfectly in isolated environment in local system. Please check my error and suggest. Thanks in Advance!
Alekhya Vaddepally 1,670 Reputation points Microsoft External Staff Moderator

2025-05-15T17:22:15.02+00:00

Hi Sahoo, Anasuya,
When you package and move your local isolated environment to azure and try to install an additional package on the runtime, the azure can still consider it as a "long -lasting operation". Combined with an overhead of network calls and subprocess execution, it can give rise to timeout errors - especially under /convert endpoints where you handle dynamic execution.

Instead of installing libraries on runtime, include all usually the required packages during the construction of your deployment. You can use a requirement.

If the dynamic library installation or conversion argument cannot be shortened, consider the Azure services designed for it:

Azure Container Apps- complete control over the environment and runtime, perfect for custom isolated environment.

Azure Durable Functions- ideal for long-run background jobs such as durable work-code conversion.

While the ideal is not long term, you can temporarily increase the timeout range via web.config or applicationhost.config, but this is a workaround - not a scalable solution.

If you look at the log's like an unknown language unknown, it can clearly be beneficial to delay or avoid abortion in passing language metadata or preprocessing signal.
Custom Container Deployment in App Service
Azure App Service Timeouts
if you have any further concerns or queries, please feel free to reach out to us.
Sahoo, Anasuya 20 Reputation points

2025-05-16T13:22:41.6633333+00:00

Thank you so much Alekhya for your suggestion. Let me try Azure Container Apps and get back to you.

Answer 1

Hi Sahoo, Anasuya,

Azure App does not support the creation of a virtual environment using Python -M Venv on Seva Runtime because:
It runs on a read-only file system for parts of the container (eg /TMP or app directory), which prevents the construction of new folders such as ./isolated_env.
This has banned permissions that limit subprocess execution and virtual environmental formation.
Since the app service already provides a different runtime for your app, you may not need to dynamically create a venv. Instead, consider running the converted python code inside a sandbox like a sandbox without the requirement of a real venv.
If you should create a dynamically isolated environment, the best approach is to use a custom docker container with complete control over the file system and runtime environment.
You can configure the dock containers with all the necessary python dependence, and your app will be able to create a virtual environment or even use tools such as Virtuulanv or Conda.
https://learn.microsoft.com/en-us/azure/app-service/configure-custom-container?pivots=container-linux&tabs=debian
https://docs.python.org/3/library/venv.html#creating-virtual-environments
If your use involves short -term execution of the code (eg per request), consider Azure container apps or Azure function premium plan, where you have more flexibility around the file system and environmental setup.
https://learn.microsoft.com/en-us/azure/container-apps/
https://learn.microsoft.com/en-us/azure/azure-functions/functions-premium-plan?tabs=portal
if you have any further concerns or queries, please feel free to reach out to us.

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how to fix error 'subprocess.CalledProcessError: Command '['python', '-m', 'venv', './isolated_env']' returned non-zero exit status 1.'

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