Bluetooth greyed out

EdMd Said:

"Bluetooth greyed out: I can't turn on bluetooth. I have a MB Pro 13 2015. Thanks."

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Boot in Safe Mode:

In Safe Mode, Login Items do not run at login, certain preferences are set aside, and damaged system files are then reset. So, once booted in to Safe Mode, wait 30 seconds, and then boot up normally, attempting another update install. For instructions, go here: How to Use safe Mode on your Mac - Apple Support

EdMd Said:

"Thanks for the suggestion, but it didn't work."

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Reset the Bluetooth Module:

Depending on your macOS, resetting the Bluetooth Module might do the job. This, however, is not an option on recent macOS version. See my User Tip: Use "Reset the Bluetooth module" to Fix Constant Bluetooth Disconnections - User Tip. View the first comment.