Grateful for any advice. Running Mac OS 10.14.5 on mid-2014 MacBook Pro 2.5 i7.
Just cancelled Office 365 sub. Attempting to reset LibreOffice as default app for .xlsx, .docx, .pptx files etc. but MS Office for Mac fired up every time, despite holding option and selecting LO as ‘everytime’.
Deleted MS Office for Mac apps to resolve issue and now when trying to open any files created in MS Office for mac I get the message: ’ “[file]” is damaged and can’t be opened. You should move it to the Trash.’
Any help appreciated. Many thanks.
Can’t help wondering exactly which application is telling you that the file is (supposedly) damaged. Is it some pernicious remnant of MS Office, or is it your Operating System, or is it LibreOffice itself that is telling you that??
Thanks for responding. It’s an OS message. Just noticed that when attempting to change default app for a .docx file it initially shows as ‘Microsoft Word Document’, then, when option-right clicking to ‘always open with’ LibreOffice the description changes to ‘3rd party formats’ and I get the ‘file is damaged’ message.
Have you tried opening the file(s) from LibreOffice instead of Finder?
Thank you. I have now, and they seem to open without issue from within LibreOffice. Any idea why that would be?
Rule #1: DON’T PANIC!
My guess is the uninstallation of Office went pear-shaped at some point. Out of curiousity how did you uninstall? Uninstaller? Dragged the app to the Trash? AppCleaner? As @ve3oat said above I think it’s also a “pernicious remnant” of Office.
Thanks @gtomorrow. I’ll come clean and admit that I couldn’t find the uninstaller on my system (certain there was one with previous MS Orifice versions) so dragged them to the trash as was getting with them starting when they shouldn’t. I just assumed (ass: me) that MS had got their act together and gone all clean and tidy.
Also thanks @gtomorrow for the solution. Will you rewrite your comment as an Answer, for the record? (As for me, I don’t have a Mac so could not help beyond my initial comment.)
@Skizz dragging an app to the Trash does in fact uninstall but that method leaves behind a bunch of satellite files and in my experience Microsoft products (like Adobe products) spew the files all over the HD, some even hidden. If you have any doubt to what you’re doing, don’t search and destroy! I can’t stress that enough.
@ve3oat thanks but Rule #1/opening files from the app instead of the file manager are so fundamental I couldn’t even consider them as an “answer”. If they were I could resolve at least 50% of the problems on this site! 
@Skizz one last note: https://support.office.com/en-US/article/uninstall-office-for-mac-eefa1199-5b58-43af-8a3d-b73dc1a8cae3
@gtomorrow Yes and I know exactly what you mean. On the other hand, getting the question marked as Answered would help to educate those users who might look for that answer before posting the same old question yet again.
@ve3oat Grateful for your help with this but afraid I did search extensively for relevant articles before posting this question and got nothing useful in results. That may be why others have posted the same question previously.
As requested by @ve3oat…
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DON’T PANIC! If a LibreOffice file, regardless of type, doesn’t open from your OS’s file manager (in this case, Finder) first launch LibreOffice and see if you can open the file(s) with
CMD-O > Open File. If that works, the file(s) are not corrupted and it is most likely a attribution resetting…that is, somehow the file(s) got associated to another program. This “unwanted reassociation” is probably the cause of 80% of similar but easily resolved problems on this site! -
From Finder, choose a LO file and press
CMD-I > Get Info...and find theOpen With...drop-down list. FindLibreOffice.appand click theChange Allbutton. Now all of the files associated with LibreOffice will open with a double-click directly from Finder. If you’d like LibreOffice to always open MSOffice files, follow the same procedure. -
DISCLAIMER: this third step is to followed only if you are an intermediate/expert computer user. I take no responsibility if something should go wrong. You have been warned.
A typical Microsoft installation will spew files all over your hard drive, some are hidden files as well. Dragging Office to the Trash will leave a slew of satellite files that may cause problems (as OP @Skizz had). Do NOT do a Search & Destroy on any files left behind you THINK may be deleted! To properly uninstall MSOffice from your computer, either follow this link or use a third-party uninstaller (I personally have used AppCleaner with very good results…i have no skin in that game, just a satisfied user.)
All the above instructions are easily adaptable to work with Windows and Linux…except the uninstallation procedure for Linux! This method will also work with any other files that open in the wrong application or if you just want to change the default program. gtomorrow OUT!
Have cleared out the various bits of MS junk as per their guidance and have amended ‘Open with’ via file info pane. Files now open from within finder but still showing as ‘3rd party formats’, which I can live with. Thanks again for your help!