Just to build on what @ D.I. Johnson has rightfully outlined
According to your image presented
The Internal Drive has a Capacity that is almost full
The computer is too busy trying to find Empty Space to save changes that are being made
Reducing System/Volume/Data is a common question.
1 - System data taking too much in MacOS Sono… - Apple Community
2 - Time Machine Local Snapshot won't delete - Apple Community
3 - Over 60% storage blocked by System Data - Apple Community
How to free up ‘System Data’ and other storage on your Mac from a fellow colleague @ neuroanatomist
Use another application to see where space is being used Storeograph on the Apple Apps Store
Suggest getting an External SSD Drive and start moving your Pictures, Videos, Music, Messages and any other large files you have control over, OFF the Internal drive and Onto the External
Understanding iCloud Drive from a well written User Tip from @ Richard.Taylor
There are two effective ways to remedy this issue:
1. Quick Fix Action as previous mentioned by @ D. I. Johnson
For Apple Silicon computers, use Disk Utility to erase a Mac.
For Apple Intel computers, use Disk Utility to erase an Intel-based Mac, then reinstall macOS.
Always make a Time Machine backup before proceeding.
Migrate only the user account, not the entire system.
Reinstall only the necessary applications from the Apple App Store or directly from the developers.
2 - Generally
When the user discovers this issue,
it’s likely because the computer’s internal drive capacity is small, such as 256 GB
Unfortunately, the user’s storage needs may have increased since the computer was purchased.
To future-proof the computer, consider spending extra money upfront on a larger drive capacity and adding more unified RAM.
Note - On Apple Silicon and newer computers.
The SSD Drive and the Unified RAM are Soldered to the Logicboard and can not be upgraded.
