Cannot open LR Catalog: Parent Folder does not allow files to be created

So I recently began experiecing the same problem described above... 

The Lightroom catalog cannot be used because the parent folder “/Volumes/xxxxxx/Photos/xxxxx Photo Library” does not allow files to be created within it.  I've been using the same MAC, external hard drive set up for years.  I have not change MACs or had a system corruption.  I verified that the read/write permissions and the privacy and security settings described below are set correctly.  The only recent change to my system was the installation of macOS Montery.  Could that be related?  Any advide would be great.  Using LR Classic

There's another kind of permissions under System Preferences > Security & Privacy that's tripping up lots of Mac users recently.  You're on an older version of Mac OS, so it may not apply to you, but give it a try:

https://community.adobe.com/t5/lightroom-classic-discussions/lightroom-catalog-cannot-be-used-because-the-parent-folder-does-not-allow-files-to-be-created-within/m-p/12883223#M270829 

In case anyone else encounters this.  I had checked that Lightroom was up to date.  I also uninstalled and reinstalled it.  And I had gone through all the permissions already to test that.  I was getting a message that there were no permissions to write in a folder where the permissions were clearly set correclty

I texted Adobe support (did not want to do that when the problem cropped up on Easter Sunday.

Their advice was to drag drag any catalog backup to the desktop and try to open it. That worked. Lightroom opened and the permissions messages stopped appearing. I sked the Tech what that fixed -- why did it work. Her response. She did not know.

Okay. So there is the possibility that the problem may recur because its not clear that anything got fixed. But, should anyone else find themself in a similar predicament.... this worked.

While you work on that Lightroom version clarification.

Another issue is to look at your rights to the folder that Lightroom is complaining about.

In Finder, navigate to that folder, Select Get Info, and look at your rights.

macOS Sierra: Set permissions for items on your Mac

In fact look at these folders as well:

• /Users/[user name]/Library/Preferences/
• /Users/[user name]/Library/Application Support/Adobe/
• /Users/[user name]/Library/Caches/Adobe/
• /Users/[user name]/Documents/Adobe/

Solutions to Adobe Lightroom Lightroom user permission issues on launch

By the way, I would not call that the parent folder, Oh it could be, but parent folder is a term in the catalogs folder panel, parent to where images are kept, could be same as where catalog is kept. Just bitching.

What version of Lightroom?

As you apparently cannot open the current catalog, Can you create a new catalog and check in Lightroom for version as seen in /Help/System Information.

Alternatively, and I am not at a computer right now, so this from foggy memory, In your Adobe Creative Cloud Desktop App, in the App tab, at the Lightroom Classic instance, you can view the version (Mouse hover over program description/Title)