The error is caused by one obligation in the group having a special character in the Description fields. Unmark the obligations for pay so you can edit them in the Invoices folder. Open each obligation and remove any special characters from the Description fields.
In addition to special characters, this can indicate corruption in an AP file, such as the ##ota. Filemaint.exe should be run on ##o* to see if any files have problems. After filemaint.exe is run, diagnostic programs need to be run in Division 00, System Utilities. Run Program name ots970, switches 1 and no parameters. This will produce report ots970.L##. Run Program name ots971, switches 1 and no parameters. This will produce report ots971.L##. If these reports are not blank, contact FundWare Support for further assistance.