My update goes through the process but doesn

nick from port dover wrote:

Although it follows the restart process etc the update remains - like an endless loop

Boot into Safe Boot Mode and try again from this environment to launch/install the update.

SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc. Login and try again

Direct download— Combo update macOS 10.15.4 https://support.apple.com/kb/DL2037?locale=en_US

You mean the “about ___ minutes remaining”?

wait for a few hours for it to complete, personally the 10.15.4 update took longer than usual for me.

if a day has ended and it’s still not done, force restart by holding the power button, but be prepared for OS corruption.