Quicktime player quit unexpectedly

You may have to restart and also choose to run Disk Utility on the hard drive of your Mac.

• Disk Utility User Guide for Mac - Apple Support

https://support.apple.com/guide/disk-utility/welcome/mac

Note sections, last one in particular: How to repair a disk

Safe mode on startup, can be done w/o Disk Utility, too.

See blue-text link below.

The later macOS has different file structures and uses space differently. So sometimes

that may get tripped up. To start Mac in Safe mode, which also helps system files and

sort some things out in the background, and re-start to exit Safe mode, helps too.

And you may have to consider updates to Catalina macOS 10.15.(2?) as 10.15.4 had been

available for awhile; and some users were able to update that to last step, 10.15.(.5?)

While none of my Macs is upgraded to the most recent macOS; some of these only

run only vintage versions of Mac OS X. I no longer run 'the latest macOS'. One has

Mojave 10.14.6; and another Mac has dual hard drives, so also has more than one OS.

(Late PPC G4 Macs and early Intel Macs are still in use here, too.)

Good luck & happy trails!🌞🎣

Delete this file:

~/Library/Preferences/com.apple.QuickTimePlayerX.plist

If that has no effect, delete these files:

~/Library/Containers/com.apple.QuickTimePlayerX/Data/Library/Autosave Information/com.apple.QuickTimePlayerX.plist
~/Library/Containers/com.apple.QuickTimePlayerX/Data/Library/Autosave Information/Unsaved QuickTime Player Document X

where "X" is a number.

NOTE: That last file might not exist every time you look into that directory.

And you've updated Catalina macOS 10.15.2 to later/last 10.15.5?

Often, if the system has been erased and new one installed, the

problem cannot help but go away. (Backups are recommended.)

Learn how to back up your Mac

• How to reinstall macOS from macOS Recovery - Apple Support

https://support.apple.com/en-us/HT204904

Choose Option-⌘-R

(Upgrade to Latest macOS that

is compatible with your Mac)

Second more recent article on topic, may be helpful:

• Reinstall macOS - Apple Support

https://support.apple.com/guide/mac-help/reinstall-macos-mchlp1599/10.15/mac/10.15

If you need to erase the old system and reinstall anew, review relevant

details in Support articles; some newer ones, say try a different method.

Learn more about when and how to erase

If parts of the existing system are somehow failed or have defects,

this would be able to replace those with an all new system folder.

Some defects or broken files if used to Migrate old stuff to a new system

could import those same defects, once again. Just saying, as it happens.

Usually this is not generally this much a problem to resolve.

(A second 'duplicate thread' on this topic likely was removed by hosts.)

Good luck & happy computing!🌤🌎

In this neighborhood there are ways of handling disks and capacities.

• How to erase a disk for Mac - Apple Support:

https://support.apple.com/en-us/HT208496

Details of article(s) were known prior to my earlier posting here.

These could factor in use of storage partitions + sub-portions there.

Volumes, containers, and the like; are addressed in such articles.

Good luck & happy trails!🌻🐝

Deleting the .plist didn't work, but deleting the files in the "containers" as you listed did work. Thank you!