Unable to install "MacBook Pro Flash Storage Firmware Update 1.0" on MacBook Pro 2015-Mid with latest macOS Catalina.

If the Flash Storage Firmware Update 1.0 was originally released for an older version of macOS, then it will not work on any later version of macOS. Apple tends to lock firmware updates to the OS at the time the update was originally released.

Boot into Safe Mode (How to use safe mode on your Mac - Apple Support) by booting with the Shift key held down and and try installing the upgrade from there.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

Hey MMughees! Did you reinstall the OS from recovery, (Command R), or internet recovery, (Command Option R)? Internet recovery should install all valid and available updates. If you already have, does the update prompt happen in a new user account? Also, when you are in System Preferences > Software update, does pressing Command R get rid of it? (This should refresh the status of the prompt, but considering what you’ve done, may not).

Hum, are you charging the MacBook Pro at the time the firmware update is attempting to install ?

Thanks for the update! I'm glad it worked for you. It is sad that Apple has made this so difficult and overlooked the possible need to run firmware updaters on later versions of macOS. It is a stupid limitation.

https://support.apple.com/kb/dl1830

Awesome! So it downloaded fine on Yosemite, and retained after Catalina upgrade, good to know!

I’d try that first. I’m also unsure if the FW update is actually compatible with this Mac or not (Don’t see why not) you can use Terminal to run all available updates in the background, or if a glitch, set it to ignore this particular update, but don’t usually see a need for that given the usual tools, hope it works out either way!