Model service specification & locked by user &

What causes this issue?

The <DS:GLOS.3526C11EAFAB52B9E10000009B38F974>model service
specification</> is being processed by user &v1&.

System Response

The system locks an object when it is being processed, so that only one
user changes it at a time.

How to fix this error?

Try again later.

Error message extract from SAP system. Copyright SAP SE.