trying to reinstall MacOS Catalina because i got the dreaded prohibition screen.

richardfromdelbarton wrote:

I made a bootable install disk. When i boot up in macOS Utilities, i click install and when i get to select destination drive, it only shows my boot drive. My HDD is visible on disk utility. I am afraid the disk is too full. if i can get it booted up i can extract the files to an external hard drive. I actually am more interested in the files than the MacBook Pro itself, ( i know, i know should have backed it up). Is there a workaround ro install the OS or to extract the information from the hard drive in recovery mode?

Back up your Mac with Time Machine

https://support.apple.com/en-us/HT201250