This file is already open or in use by another applicatication

[#1]

In Acrobat Reader DC:  I have 3 computers sharing WiFi (all have Windows 10, version 1909) with the latest Firefox (74) set to open .pdf files in the browser. 

I opened a file in the browser on 1of the computers, then downloaded it and saved it.  Now, on the other 2 computers, when I attempt to 'open with Adobe Acrobat Reader DC' a displayed file from the internet, I get the message:  'There was an error opening this document. This file is already open or in use by another application'.  I can 'save file' as usual and then open it, but can't open it directly.  If I set the browser to open .pdf 's in Acrobat, I get the same message.  I removed DC from one of the affected computers and reinstalled it with no effect - I still get the message.  The original computer doesn't have this problem.  Anybody have the same problem and found a fix?

[#2]

In Acrobat Reader DC:  I have 3 computers sharing WiFi (all have Windows 10, version 1909) with the latest Firefox (74) set to open .pdf files in the browser. 

I opened a file in the browser on 1of the computers, then downloaded it and saved it.  Now, on the other 2 computers, when I attempt to 'open with Adobe Acrobat Reader DC' a displayed file from the internet, I get the message:  'There was an error opening this document. This file is already open or in use by another application'.  I can 'save file' as usual and then open it, but can't open it directly.  If I set the browser to open .pdf 's in Acrobat, I get the same message.  I removed DC from one of the affected computers and reinstalled it with no effect - I still get the message.  The original computer doesn't have this problem.  Anybody have the same problem and found a fix?

[#3]

I have a co-worker with the same problem.  Haven't found a solution yet.  Her setup is Windows 10, Adobe Acrobat DC, using Firefox.  She too can save the PDF to her hard drive and open it but if she tries to open the file from Firefox (which is set to open PDFs using Adobe) she gets the error that the file is in use.  She has told me that if she closes that error window and tries again it will open the second time.  I've asked her to check some different settings, try a different browser so as to narrow this down.  If I find anything interesting I'll report back.

[#4]

Thanks for the info. Trying again doesn't work for me. Everything works fine on the computer that originally downloaded the file, but that one doesn't get used much - it is in the shop. The problem still exists on two other computers. I hope you find something.

[#5]

Have you tried with a different browser?  I had my co-worker try with Edge since she already had that on her computer and it worked fine.  I'm wondering if some combination of recent updates (be it Adobe, Windows, and/or Firefox) caused some sort of glitch.  I'm probably going to have her do a complete uninstall/reinstall of Firefox next.

[#6]

The problem seems to have cleared up after changing ISP's and routers. When it was in effect, it didn't seem to be browser related - I think I checked at the time, but it is working fine now.

[#7]

We have over 300 users on our network and so far this issue only seems to affect about 6 but once it happens for that user it happens every time.  They can save it to a local drive but not a network drive.  I saw the comment below about changing ISP but that is not possible in a network enviornment.  our default is chrome.  Any ideas yet from anyone else?

[#8]

I had the same problem right NOW. After a few times trying to save the PDF document, I copied the document to the desktop...and tried saving it there. It worked a charm. The issue for me is that the depth / hierarchy of folders where it was located was too deep. Meaning that the limit of characters in its address was past its max (I cannot remember the write technical terms at this time, but hope that you catch my meaning).

So try and copy the offending file to the desktop and see if that is not the issue. If so, investigate the number of folders and length of the folder names that may be causing the fault.

[#9]

I have had he same problem on two desktop computers running windows 10 and Firefox. I still have not found a solution but the downloade file is always in the download folder so can be opened from there as soon as you get the message. It will be found right away by clicking the download blue arrrow.