We started seeing this Save error on 12/30/24 with no change on our end other than keeping Adobe Acrobat Pro and Reader up to date with current version (2024.005.20320 64-bit). PCs OS is both Windows 10 and 11 pro. Our network share is DFS but testing done on non-DFS storage doesn't exhibit this issue nor does local storage.
Users edit a file on their network share and click the Save diskette icon expecting for the changes to save. Instead, they get the following dialog boxes and the following error:

Confirm Save As: Name.pdf already exists. Do you want to replace it? (Yes/No)
Adobe Acrobat: The document could not be saved. Cannot save to the filename. Please save the document with a different name or in a different folder.

Followed by the Save As screen with a random filename ending in .tmp.
I understand that turning off Enhanced Security in Acrobat is the fix for this but that's not going to happen. I also understand this error has been reported as far back as 2013 and another issue with DFS and opening multiple PDFs has also been reported.

I'm here today to inform Adobe and the community that this Save/Save As bug is back as of the last Adobe update. Testing we've done shows this is not a permissions issue. The error is reproducible at will. The number of folders deep the file is located isn't related.