An idea that MAY work to install and/or run old programs in Windows 10... works for some, not for others
Do you have a back up of the corrupt catalog? If so, try that.
trying to move LR 5 to a new computer with Windows 10. When trying to open catalog, I get an error message that the catalog is corrupt and cannot open . Tried several times.
You don't MOVE LR to a new computer. You install it on the new computer then you Copy over your Catalog file to the new computer.
If that is what you have done then how did you copy the catalog over? USB thumb drive or external HDD? First go back to the old computer and try opening that same catalog. Does it open OK? If it does then whatever you used to copy it from the old computer to the new computer corrupted it. Use some other USB drive to do the copying.