FCPX Started Crashing

Hello all!

I'm having an issue where FCPX crashes every single time I open the project I am trying to work on. The project appears to load normally and then when I drill down into the event / project it suddenly crashes. I just recently updated (due to necessity) to Big Sur and this is when the problem began.

I am running the following...

Mac Pro 7,1
Mac OS 11.2.3
FCPX 10.5.2

If possible, safeguard your prior copy of 10.5.1, whether by Time Machine or any other available method. When upgrading it's a good idea to rename or copy the current Final Cut Pro.app bundle, (and also any important libraries) since that enables easy rollback in case of problems.

Make an additional safety copy of all FCP auto backups, which by default are in /Movies/Final Cut Backups. Those are not very big, just make an external copy of them all.

As a standard debugging procedure, make sure you have rebooted the entire machine, then reset FCP preferences (item 11 on this page):  support.apple.com/en-us/HT203477

Make sure all libraries and media are on either APFS or HFS+ (Mac Journaled OS Extended) disk volumes, not ExFAT, NTFS or anything else.

Verify you have at least 20% free space on all disk volumes.

Verify you are on the latest version of Apple Pro Video Formats. That is upgraded in System Preferences>Software Update. You can inspect your version in About this Mac>System Report>Software>Installations, then scroll down to Pro Video Formats and read the highest version number. On Catalina the latest version is 2.2.1.

Make sure you have  upgraded any FCP plugins, esp. those from CoreMelt.  You can update those using their installer page: coremelt.com/pages/downloads

Any plugins acquired from FxFactory can easily be upgraded using their app.

Any plugin from Pixel Film Studios should be meticulously scrutinized, as they have caused many problems.

If you are running the Chrome browser, do not run that while FCP is running. There have been long-term issues with that; it may now be fixed but I don't know for sure. Verify in Activity Monitor that Chrome is not running before you launch FCP.

After doing that if it still crashes, when the crash dialog pops up, please select/copy/paste the entire text contents to a text file using TextEdit, then upload as an attachment to a new post. Please do not post it "in line" because the forum software doesn't handle it well.