Why is Final Cut Pro so unfriendly when trying to reopen a Library or project?

This is very unusual behavior you describe.

What version of FCP is this and what OS are you running on?

Are you using the default storage location for Libraries?

Have you designated the storage location of your libraries to a removable storage device or cloud service?

As a test, if you trash your FCP preferences* and then open the app so that it is in the default configuration with a new untitled library, can you successfully name, close and reopen a library?

*AI Overview:

To trash Final Cut Pro preferences, quit the app, then hold down Option+Command while relaunching it from the Dock.

A dialog will appear asking to delete the preferences; click to confirm, and Final Cut Pro will restart with default settings, resetting your custom window layouts and other personalized settings.



Step-by-Step Guide:

Quit: Final Cut Pro.

Press and hold: the Option and Command keys on your keyboard.

While holding the keys, launch Final Cut Pro from the Dock.

When the dialog box appears, click the Delete Preference button.

Final Cut Pro will then restart with its default settings.

What Happens When You Delete Preferences:

Resets Settings: Your custom window layouts, workspaces, and other personalized settings are reverted to their original default state.

No Data Loss: This action does not delete your libraries, media, projects, or any edited footage.

Diagnostic Folder: A folder named "Video App Diagnostic" may be created on your desktop, containing information and backups of the previous preference files.

After Deleting Preferences:

You will need to reopen your libraries from their saved locations.

You may need to reconfigure any custom preference settings you had set up.

MtD

The "Recents" list in macOS and apps running on it will not show anything that is offline.

Did you disconnect the drive the Library was on?

Do you know exactly where the Library is?

If you are asking how to find FCP libraries, in Finder do CMD+F, select "This Mac" and in the search box at upper right enter:

.fcpbundle

If you want to exclude the FCP auto-backups, use NOT terms like this:

name:.fcpbundle NOT name:cdt NOT name:cst

If you want that for all FCP libraries modified after a certain date:

name:.fcpbundle modified:>10/01/25 NOT name:cdt NOT name:cst

If you want all FCP libraries (including backups) created in January of last year:

name:.fcpbundle created:>=01/01/24 created:<02/01/24

If you want all FCP libraries (not including backups) that were *added* so far this month. Note this is for US CDT. For other time zones, add additional three-letter NOT terms to exclude those.

name:.fcpbundle added:>10/01/25 NOT name:cdt

To save any of these or any others you devise, just press the "Save" button at upper-right in Finder. It will appear as a gear in Finder's left sidebar. Click on the gear to run the query. Right-click on the gear to see options.

Below is a rudimentary zsh shell script that recursively scans all FCP libraries and lists all projects. Starts search from current folder (typically ~/Movies). Some of the optional features don't work yet, but at least it will list all of them.

1. Put fcp-project-find.zsh script in ~/Movies
2. Grant execute access: chmod +x fcp-project-find.zsh
3. Run it:  ./fcp-project-find.zsh

How come YOU don't know where your libraries are stored?

Final Cut Pro usually remembers the libraries used recently, but it is incumbent on the user of a professional software to have their media and libraries organized. I am constantly shocked by how many users have no clue of what a hierarchical file system is. I blame the iPhone for that.