Moving this discussion to the Photoshop Lightroom forum.
Tell us the details
Exactly what steps in Lightroom did you try, emphasis on EXACTLY. Please use the Lightroom name of whatever functions, buttons or menu commands you used.
Exactly what is the error message? Emphasis on EXACTLY.
okay here goes
computer- imac 3.5 Ghz, 27 inch, core I7, memory 32GB, OS x 10.9.5
1) PSE12 (latest version) was already installed as was LR4. I installed LR5.7 ( i did not remove LR4 until i am sure LR5 is working) and opened it up and under the files tab clicked on "upgrade photoshop elements catalog" i got this message- "Lightroom encountered problems when trying to upgrade the Photoshop Elements catalog and cannot complete the operation."
i tried this with PSE12 open and closed.
2) i opened the PSE12 catalog and ran repair which found no errors but i had it repair it anyway. i tried it again with the same error message.
3) i chatted with adobe help and they gave me this link to try Lightroom cannot upgrade Elements Organizer catalogs
this is a help document from adobe.
4) i tried solution #1 same results
5) solution #2 does not apply since my program is on the main hard drive of my imac
6) solution #3 was done already- same error
7) solution #4- i removed both files (plist) to my desktop and PSE12 would not load the catalog. i got an error message and when i clicked okay a blank PSE12 window came up. i re inserted the plist file ad it works fine. i assumed that that as the correct plist file so there was nothing else to do. Idid not try to convert the pse12 catalog whit out the plist i removed since it would not load. I will say that pse12 had added another plist to replace the one i removed with a one higher number at the end. i removed this when i put the original one back.
that is where i am now.
Seems like you have done the right things.
All I have is a wild guess at this time ... remove any videos from the PSE catalog, and try again
I removed the videos, still the same error
i even uninstalled PSE12 and deleted the catalog and then reinstalled the program. i then brought in just a few pictures and still got the same error.
any other thoughts?