When autosave is turned on Acrobat periodically writes .tmp files to the autosave location containing annotations since the last time the file was saved. If Acrobat is forced to quit without saving the open file, upon restart it detects the presence of the .tmp file and offers to restore the changes. At that point that .tmp file is still in the autosave folder.

Immediately after the user accepts that offer, Acrobat deletes the .tmp file and returns an error saying the file cannot be found or read and as a result all changes have been lost.

This problem has existed for at least 2 or 3 years and is apparently a common experience as evidenced by numerous complaints revealed by a Google search for this issue. It is an extremely serious issue as it can wipe out hours of work. For me the problem often occurs when I have left my computer for a while and Windows 10 applies updates and restarts.

This is easily reproduceable and I have tried all sorts of things to work around it, like copying the .tmp file before restarting Acrobat. but nothing works.

One of the most frustrating parts of this is even if I preserve the .tmp file, Acrobat does not provide any function or action to manually import the annotations. The code must be there, otherwise the autosave function would have no purpose. So even if you cannot easily fix the bug, how about just providing a command line function or built-in action to initiate the process? I have a .tmp file now with a number of time consuming annotations which will take me hours to re-do.

How about either restoring it for me or giving me a little tool to do it?

I can provide the files if you want them.

Thank you.
Acrobat DC, latest version
Windows 10 Prof 18363.1379