Application folder is 17.5 GB. 373 GB in System Settings

FWIW ... System Data: This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

It includes:

• Time Machine local snapshots. These are common with laptops when you are using TM, but do not have a backup drive currently attached.
• Spotlight indexing. You can rebuild the index. Rebuild the Spotlight index on your Mac - Apple Support
• iCloud storage of infrequently used files

A couple of things you can do to reduce this category are:

• Boot up your Mac in Safe Mode, then shutdown, and then, boot up again in normal mode.
• Delete the local snapshots. You can do this via commands in the Terminal.
  • sudo tmutil listlocalsnapshots /
  • tmutil deletelocalsnapshots <enter the snapshot from what you found in the first command>

For the record...

That "Storage" display organizes data by category, not location. I'm not even sure if it is limited to the boot drive. It may display storage on any connected drive. But regardless, applications can be stored anywhere. The size of the "Applications" folder itself is irrelevant.

Furthermore, I don't know if that "Applications" category includes application data. But again, this is immaterial. It is always dangerous to delete files and folders inside any hidden folder, especially a "Library" folder. Manually deleting files and folders inside a "FileProvider" folder or similar is extremely dangerous. You will lose data. Your data losses may not be limited to the computer itself. Your data loss and/or corruption may extend to one or more cloud services.

How many Users do you have set up at  > System Settings > Users & Groups?

Have you installed any Cleaner/Optimizer apps?

When you click the "I" on the Storage settings for Applications, are you able to see any discrepencies from your Application folder.

Use Disk Utility to check all container in your boot drive for Time Machine local snapshots. Delete all but the latest. How is shown here:

I want from about 35 GB free space to over 250 GB free space.

There is another post about this issue. The problem was solved by determining what was filling up the wharf folders and moving those to a deeper folder location in the Documents folder. You could also move it out of iCloud Drive folders if you don’t need it synced across devices. You have to disable Desktop & Documents in iCloud Drive before moving anything. It may have worked solely because they deactivated the sync feature and re-enabled it.

If I find the post I’ll link to it.

Make Time Machine Backup  before doing  anything, in case 🤞

Aside from what has already been suggest on other contributors

Locate backups of your iPhone, iPad, and iPod touch

@ Barney-15E

From an External Link on this Wharf Folder, if that may help

https://apple.stackexchange.com/questions/452449/wharf-folder-on-mac

Thanks for more info. By deduction I realized what you said in your second paragraph. Dangerous yes, but a computer that crashes and become almost non-functional is dangerous too. Apple could be more helpful with these situations.

PS As I said earlier, I have other backups and this is not my primary computer. I deleted 400GB, rebooted and computer seemed to work (doesn't mean data isn't disappearing) for an hour. Then emptied Trash (I stopped watching after it showed 1.5 million files deleted). Rebooted and now working. We'll see.

MtnBiker wrote:

I have other backups and this is not my primary computer. I deleted 400GB, rebooted and computer seemed to work (doesn't mean data isn't disappearing) for an hour. Then emptied Trash (I stopped watching after it showed 1.5 million files deleted). Rebooted and now working. We'll see.

Understood. But it would be a good idea to consider this a wake-up call and review your data storage and disaster recovery procedures.

I'm still in the middle of my own (Apple-induced) disaster recovery wake-up call. My incident included restoring from backup and then discovering that either my backup or my restored data was corrupt. My continued recovery efforts may have corrupted my iCloud data as well. The iCloud data is the only part I worry about because it gets propagated to other devices. I have plenty of backups and manual archives. But I still need to write some scripts to confirm that my existing data is valid.

I am so thankful that I bought a new MacBook Air recently. Dumb luck on my part.

Yes and he was lucky to have no problems after deleting the files.

I am going to delete the FileProvider/0ED74972-6676-4BDA-8BE1-DFEC7D49708B folder and see what happens.