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I also deleted Zotero.dotm from its home folder, and then manually reinstalled it following each step. I read this thread, and I followed each step. Just to be sure, I checked with my university's IT director and our Zotero librarians, and their Word Processor Add-In is working just fine on both PCs and Macs. I am having this same Run Time Error: 5 problem on my Macbook Pro running Catalina, and my Mac Mini running Big Sur. This problem is recent no problem up until Nov or Dec of 2020. Ran a Debug (Debug ID: D264744190) - no luck.
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I updated Word, closed it out, rebooted my Macbook - no luck. I tried uninstalling Zotero and then re-installing it - no luck. When trying to teach my students this feature in Word (both last week and today), I receive a pop-up message: Run Time Error: ‘5’ Invalid Procedure Call or Argument. Until recently, the Microsoft Word Processor Add-In has worked well, allowing me to easily add endnote/footnotes and bibliographies through the Zotero menu in the Word ribbon pane. I have been using Zotero for about 10 years since I worked at CHNM.
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