What is your OS?
Is the catalog on a internal drive?
In case you are on Windows: If you run Lightroom "as Adminstrator" (right click on the exe, run as..), are the errors gone?
Hello, I'm having exactly the same problems with Lightroom CC. I am using Mac Os X El Capitan 10.11.1 and I am storing my catalog on the external drive which has plenty of space available.
Hope something can be done with that. I am starting to loose faith in this application.
I upgraded to El Capital 10.11.1, after which I started noticing the problems. After a period of time, I downgraded back to Yosemite using my time machine. That, however, did not solve the problems. So, my operating system is now Yosemite (10.10.5) and I am running Lightroom 6. The catalog is on an external drive and I back it up to an internal drive.
Please create a new, empty catalog, see if it works with it without errors and let us know.
I made a copy of my Lightroom 6 catalog (and related files) and moved them to a different external hard drive that has more space. I read in a post that it is not just the destination location of the back-up (which for me is my internal hard drive), but also the source location of the catalog (which for me is an external hard drive) that must have enough space and that LR applies a multiplier to the size of the catalog in determining whether there is enough space. This appears to have fixed most of the issues, so I can back up the LR catalog now. I can also work in LR without the constant "error reading catalog" messages. The healing tools also work now. The only thing I have noticed that is still a problem is when I go the "Create Saved Book," I get an error message "An internal error has occurred ?:0 attempt to index a nil value." Do you have any suggestions as to how to fix that problem? Thank you very much for all of your help.