Overall budget exceeded by &2 for &1

What causes this issue?

The overall budget is exceeded by &V2& for the GM account assignment
&V1&. Availability control on outgoing amounts raised this message for
the following combination of availability control ledger and control
object:
&V3&&V4&
<ZH>Note:</> The control object is defined for a grant/fund/sponsored
program/sponsored class/budget time slice.
DEFINE &N& = '012'
INCLUDE GMAVC_OVERALL_MESSAGE_EXT

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.