Start up issue

eoin80 wrote:

Progress bar stuck at 100% completed, need solution to fix.

Boot into Recovery (Command R) and from the dropdown menu: Utilities>  Disk Utility> run the First Aid on your Macintosh HD (and the "Macintosh HD-Data" volume as well if Catalina) If errors are found and repaired, run again until no errors reported.

Recovery: https://support.apple.com/en-us/HT204904

To trouble shoot further you can:

Try a 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 test. Reboot and test will take a little longer as caches get rebuilt.

This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.

Test issue in another user (or guest user) account  https://support.apple.com/en-us/HT204443

This will tell you if it a universal issue or isolated to your user/admin account.