The state & cannot be reached

What causes this issue?

There is neither an event nor an element within a module assigned the
attribute 'next_state=&V1&'.

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?

Check if a typing mistake has caused the error.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.