We get this error when we try to save a new task or an updated schedule time in IM-> tools menu->distribution.
Unspecified error
20.4 CU2 and later with any version of IM over 4.0
This appears to be a time zone conversion issue when you set the time.
Set the OS time zone where IM is installed to GMT and restart IM.
Note: If IM is installed on a machine with a DX UIM Robot (or the primary hub) do not change the time zone as this will cause issues with the timestamps on QoS and alarms.
In that case, install IM on a separate machine that is set to GMT time zone and not part of the DX UIM domain.