How to Fix MacBook Pro Black Lines on Screen?

There are various solutions you may attempt if you notice black lines on the screen of your MacBook Pro:

Step 1 - Restart your MacBook Pro: Restarting your MacBook Pro will sometimes cure the problem.

Step 2 - Update macOS: Make sure you are using the most recent version of macOS. Check for any available updates by going to the Apple menu, System Preferences, and Software Update.

Step 3 - Reset the PRAM and NVRAM: Resetting NVRAM (non-volatile random-access memory) or PRAM (parameter random-access memory), which both hold different settings and preferences, can occasionally fix display problems. Shut down your MacBook Pro, switch it on, then immediately hit and hold the Option + Command + P + R keys until you hear the starting sound twice. This will reset the NVRAM/PRAM.

Step 4 - Check for loose connections: Ensure that all connections and wires are safe and correctly plugged in.

Step 5 - Run Apple Diagnostics: To check for any hardware faults, utilise Apple Diagnostics. Your MacBook Pro should be powered off, then turned on while holding down the D key until the Apple Diagnostics screen displays. Run the diagnostics by according to the on-screen directions.

Step 6 - Contact Apple Support: Contact Apple Support if none of the aforementioned fixes work. If your MacBook Pro is still covered by warranty, they can suggest a repair or replacement.