Since updating my Macbook Pro Mid 2012 has been too slow. Also it has restarted unexpectedly a couple of times now, how can i resolve this. Tries contacting apple support but my serial number is invalid apparently.
MacBook Pro 13″, macOS 10.15
Did you encounter any issue while updating?
Use Apple Diagnostics to test your Mac - Apple Support
Also try safe mode for troubleshooting: How to use safe mode on your Mac - Apple Support
I hope it was not typo when checking with your serial number.
"Apple registration numbers and Apple hardware product serial numbers might have the number "0" (zero), but never the letter "O." "
Hope it helps.
In addition to the great advice that Sharhari has provided you, I suggest that you run an EtreCheck report. EterCheck is a diagnostic app that can help locate any potential issues your Mac may have. If you need assistance with interpreting its results, you can post it here.
Ref: Using EtreCheck to Troubleshoot Potential… - Apple Community
Slow performance
