I've seen this issue in the past when the following occurred:
- If you select the file in the Finder and double click it, it remains 'active' somehow.
- Then issues with saving might occur.
- I've seen that happen on Windows and Mac OS
Have not seen this issue for a while, but can you try the following:
- Don't select any of the PDFs in the folder.
- Launch Acrobat, then choose File > Open and navigate to the folder that contains the PDF file.
- Make the change, and then try a Save As, and see if it works?
If that doesn't work I'd look at testing and possibly repairing the file permissions on your system.
- see: Resolve issues caused by changing the permissions of items in your home folder - Apple Support this might be helpful. Please ensure you run a full system back-up prior to making system level changes so you have a roll-back option in case things go haywire ;-)
Unfortunately none of the hints do help in this case – my pdfs just behave different to your experience. Also, I have this issues in the last weeks, or 2-3 month only, whereas you did not have them recently but more time ago. Nevertheless I did the open-method-tests:
My results with the 2 methods to open a PDF before "save as" with a new filename:
It works fine unless a PDF has been opened before – independent of the way to open it.
If I rename a PDF in the finder and open it 1st time in Acrobat then I am able to save as into the same folder.
As soon I open this PDF a second time – either from finder or from Acrobats open or recent files menu – then I am not able to save as in the same folder and I get the error mentioned above.
I can choose any other folder (even within such a problematic folder) to save as – and, also, I can switch between two folders to continue a save as several times for testing. But I HAVE TO switch to be allowed to save as. That means very clear it is not a problem of rights on system level but must be a misinterpretation of Acrobat.
This issue also appears if I quit and restart Acrobat in between. That might mean the problem occurs as soon Acrobat has a file name and storage place in its recent files list.