I keep getting a pop-up "Instalation failed" on my macbook ,how do I fix this?

Hello Bloodycherries,

​Thank you for using the Apple Support Communities. Keeping your software updated is always a great idea. I see you've been running into an "Installation failed" while trying to install what sounds like two different updates. Is that right?

Since this has happened with a supplemental update for macOS Mojave, and with macOS Catalina, it sounds like it will be a good start to repair your startup disk using First Aid. You can do this by following the instructions here: Repair a storage device in Disk Utility on Mac

Once you've run First Aid on your startup disk, click Apple menu () > Restart to boot back up, and test it out.

Feel free to post back here with an update if needed. The community may be able to further assist.

Take care.

first backup your files then go to the rcovery mode then reinstall your macos i think it will work