Timeout of document

I saw that timeout of document by default is 60 minutes.
However, sometimes I see the “Missing document instance.” message before this period of time.
Is there any explanation for this?
How the timeout is affected?


I have been working on trying to replicate the error but without success. Could you send us a simple sample project with your configuration where this error is happening? If there is any IIS cache configuration in your development environment that is affecting, also include it for further testing.

Thanks for your help.