is "Runtime Error 5" the entire error message? I don't think we've ever seen this and it's a bit of an odd error message from Word or Zotero.

Hello,

I have a similar problem.
This same message appears in Word 2016 under Windows (France).
Unfortunately, I don't know what to either..

The Mac Word plugin hasn't changed in months, so this would have to be a change in a Word 2016 update or something else on your computer. People have gotten this somewhat randomly with older Word versions, so I suspect the latter. You can try closing Word and (backing up and) deleting the Word preferences in ~/Library/Containers/com.microsoft.Word/Data/Library/Preferences/ or ~/Library/Group Containers/UBF8T346G9.Office/.

And to be clear, this happens in new documents as well?

As far as I know we've never been able to reproduce this or recommend a consistent fix. You've probably seen the old thread on this.

You could try a new macOS user account. If that works, you could transfer your document and Zotero data over for the duration of the writing.

Did not help. Same problem with Word 2011 in a new macOS user user account. Interestingly (and perhaps this helps tracking this thing down), installing the Zotero add-in from the button in the Zotero settings dialog did not do anything – no Zotero toolbar in Word. Only when I manually load zotero.dot from "Tools -> Templates and Add-Ins..." the toolbar will show up. However, I will get the same problems. To be specific: The error "5" mentioned above only applies to Word 2016. Word 2011 just crashes with this error when clicking on *any* of the Zotero toolbar icons:
Microsoft Error Reporting log version: 2.0

Error Signature:
Exception: EXC_BAD_ACCESS
Date/Time: 2016-12-30 00:16:42 +0000
Application Name: Microsoft Word
Application Bundle ID: com.microsoft.Word
Application Signature: MSWD
Application Version: 14.7.1.161129
Crashed Module Name: unknown
Crashed Module Version: unknown
Crashed Module Offset: unknown
Blame Module Name: Visual Basic for Applications
Blame Module Version: unknown
Blame Module Offset: 0x00252c26
Application LCID: 1031
Extra app info: Reg=en Loc=0x0407
Crashed thread: 0

It there anyone out there using the Zotero word-processing plugin with Standalone Zotero on macOS 10.12.2?

Yes, of course — these aren't general problems.

I tested Zotero with LibreOffice on Sierra recently. You should revert to the latest version of LibreOffice. You also currently need the JDK, not the JRE:

https://www.zotero.org/support/word_processor_plugin_troubleshooting#libreoffice_51_on_macos_1011no_response_from_plugin

I've clarified this on the installation page.

Dan, thanks, as for the Word error:

>> Office 2011 may have been installed without Visual Basic for Applications. If you did not select Visual Basic for Applications during installation, or if you're not sure, reinstall Office 2011, making sure to select this option. <<

VBA was checked and is installed.

>> A character with an accent or diacritic may be present in the path to Microsoft Word (e.g., in the name of your hard disk). <<

This is not the case here.

>> The OLE Registration Database may be corrupt. Delete the OLE Registration Database, located in Home/Library/Preferences/Microsoft/Office 2011. Word will regenerate this file the next time it is opened. (On Lion and later, the Library directory is hidden by default, but you can open it by holding down the option key and selecting it from the Go menu.) <<

There is no folder named "Microsoft" in my Preferences folder (in neither of the Library folders, user and system), so I cannot delete this database.

I will try now the LibreOffice solution you suggested, but I would very much prefer not to migrate to LibreOffice at this point (I have a 180+pages dissertation which looks like crap when opened in LO, but that's another story).

Did you uninstall the JRE before installing the JDK? (But anyway, yes, I wouldn't particularly recommend switching to LibreOffice at this point.)