When a payment is saved with an application of "Unapplied matching gift payment," users can then return to the payment later and update it to be applied to the correct outstanding matching gift claims.
When the payment is posted and users make that application adjustment in the "Edit posted payment" form, they are able to save the adjustment successfully in versions 2.91 and 2.94 as long as the adjustment post date is in an open period. However, in version 2.93 users receive the error:
Data could not be saved. Post date must be in an open period.
As with every version, users are also unable to make the adjustment via the Reconcile matching gifts task. This means that it is not possible to make an adjustment to a posted payment in a closed period at all without re-opening closed general ledger periods.
This is particularly problematic when users need to change the application from "Unapplied matching gift payment," to a specific matching gift claim, which happens frequently.
Download and install the latest patch, which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.