An Azure service that is used to provision Windows and Linux virtual machines.
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There are several reasons for running into OS Provisioning Time out problems like Provisioning agent issues, Issue with the custom image, other potential host side or extension issue etc.
Please make sure that all the steps in this document are followed correctly.
Usually this Time Out error happens when the platform has not heard back within 40 minutes from the VM guest OS during provisioning of the VM.
One more reason could be with the VHD incase if it was created from a running VM.
Unfortunately, the only resolution you have for this scenario is to rebuild the VM. Please refer this document.
Reference of common error codes of VM: https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/error-messages
Hope this helps.
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