After Effects hangs on file open

[BrigitteRoars]

I was working perfectly happily in a project yesterday but when I open it today it takes a long time then flashes up this window which crashes Adobe After Effects:

What's odd is it also affects the last two autosaves. I've cleared the cache, restarted, reset prefs, tried importing into a new project, removed new footage (from the time period after the last working copy was saved) etc. but nothing will fix this. I'm going to have to work from an older version for now but I'd really like to know what this problem is as I've lost crucial time on the project because of it.

[Mylenium]

Impossible to say much without any specific info about the contents of the project. Start by offlining any imported footage source by moving them to a different folder and, assuming the project should open thereafter, reload/ reconnect them thereafter. Everything else will require better information.

Mylenium

[BrigitteRoars]

Apologies, what more would you like to know? Offlining footage unfortunately didn't help - the file still wouldn't open.

The assets were mostly gifs with some pngs and an mp3. I've since replaced the gifs with pngs suspecting they might be the culprit, so far this file is still working.

[dj.summitt]

Do you have a different system you can test it on? If you offlined all footage, audio and video, it could be a plug-in or script that was added. When you try to import are you just Control + I or using Media Browser?

[Dave_LaRonde]

In cases like this, I restart my machine as my first diagnostic step.

[BrigitteRoars]

Thank you Dave! I did try restarting too.

I asked a colleague to try the file and he had the same problem. We're both on MacBook Pros (2017) though.

I didn't add any plugins or scripts.

I'm importing by double clicking in the media browser.

P.S. the file in which I removed all gif assets is still working so I'm thinking it was a problem with one of the gifs - strangely though the earlier autosaves had all gif assets and they still work.