Save failed. Material master for &1 is locked

What causes this issue?

Internal error. The system cannot update the table for master data.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Wait a while and try again.
Start the application again.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.