my time machine back up stalled when almost complete

MARYJAG wrote:

FInally backing up with time machine and it stalled towards the end. how do I proceed?

Trouble Shooting Time Machine

Time Machine troubleshooting on Mac - Apple Support

If a Time Machine backup takes longer than you expect

If a Time Machine backup takes longer than you expect - Apple Support

I will add—

"Time Machine has completed a new backup for you, or get a message saying it can't create the backup,"

or “failed to complete the backup, ” or “Preparing backup”

This message reappears most likely the TimeMachine disk is operating in a state of failure and will continue to fail with increasing frequency, in this case replace the drive.