canongear wrote in post #18530000
Now after double tapping the Lightroom Catalog Icrat icon again, i'm now getting this instead of the error message.
Back when you had this showing was Lr running with a catalogue called Lightroom Catalogue? When Lr is running the catalogue name is shown in the top left of the main toolbar across the top of the program window, and at least in Windows, in the main window title bar.
If Lr was not running at the time the issue that you have is that you have a rouge catalogue lock file. The file that is the problem is the one on the right hand end of the image: Lightroom Catalogue.lrcat.lock. As long as Lr is not running all you have to do is delete that file. This should then allow Lr to open the catalogue when you double click the .lrcat file.
One other thing that could be causing issues is that when Adobe introduced Lr CC Classic they introduced a new catalogue format, that uses a compressed version of the database file, along with a new process version that would also require a catalogue upgrade. If you initially installed the latest version of Lr, and it had problems with the lock file, then you ended up installing and trying to use an older version of Lr it would fail to recognise the existing .lrcat file, and give you the error messages about being unable to find the correct .lrcat file.
Since you are only just installing Lr I would suggest that you uninstall all versions of Lr on your system. Then delete all of the files in the folder shown in the attached image above, including the Lightroom Catalog Previews.lrdata folder, and all the subfolders you might have. Then just start over by installing the latest Lr CC Classic 2018.
When you import images from your existing RAW files that have been edited with ACR in the past, Lr will read each of the .xmp files that are associated, and pick up all of the settings and metadata and apply it to the image in Lr. So all of your existing work that you did in Bridge/ACR/Ps should automatically be included in Lr. It will take quite a while to read them all in if you have a lot of images already on the computer. So it might be an idea to just leave that running overnight. Then when you start to use Lr, you may well open existing images in the Develop module and notice that some of the latest editing commands are not available. This will be because they had already been edited in an older Process Version. You would need to change the PV to the latest one to enable the new tools for the image.
Alan