Association quantity cannot be increased as the open quantity = 0

What causes this issue?

You want to increase the association quantity.

System Response

The association partner has no more open quantities. The association
quantity cannot therefore be increased.

How to fix this error?

Correct the quantity you have created.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.