In a revenue update batch, users can update information about existing revenue, including pledges. When pledges are updated, it is possible to choose to update paid and unpaid installments for the pledges as well. While it is possible to manually update the designation on a pledge and its installments directly from the pledge revenue record, if users attempt to do this via a revenue update batch they will receive a "The installment splits must balance to the pledge" message when validating.
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.