Post a crash ID from Help/More Troubleshooting, Crash Reports. An ID is a string starting with bp-...

Are pdfs set to open with the built-in viewer or an app like Adobe? Preferences/General/Files & Attachments: delete the Action for pdf, restart TB, and try to open a pdf.

Thanks. bp-673b2240-43fa-43e8-9b56-b86f30211014 is the first one bp-4c08a63a-9c69-4077-b352-e0ad60211015 2nd bp-1b6a727a-7951-4fb3-bc7e-86d730211015 3rd PDF's were being opened in TB's viewer; works OK if I choose another app. I deleted the action and restarted. It asked me to select an app to view the pdf and it wouldn't let me choose TB's viewer without Browsing for it. It opened ok in Acrobat Reader. I changed Preferences to open pdf in TB's viewer, then tried again to open the file and it crashed again. Anything else I can do?

I can pm one of the pdf files that causes the problem if needed.

Not sure why it crashes only with TB's pdf viewer. I see Bitdefender in the report. Is the TB profile folder excluded from BD scanning? BD might not be a factor, although it's a known source of other kinds of interference. But it looks like it happens only with some pdf files, which the TB viewer can't handle.

Given the large number of apps that create pdfs, I wouldn't know how to analyze one that causes this crash.

Thanks. But no BD scans that folder but I don't have BD's antispam protection on. I tried turning off all BD protection, and still get the same results.

I can pm the pdf if that helps anyone there. Let me know if you think of anything else to try.

In case it helps anyone, the pdf was created by Adobe InDesign 16.4 on a Mac

I think the TB pdf viewer is based on the one in Firefox, and if you want to get the attention of the relevant developers, the best way is probably to submit a report on Bugzilla.