vss error 8193 ws2012

We are using WS2012R2 for our virtual DC1 on hyper-V, we are taking full backups using windows backup services to external hdd connected to host machine, backups are completed successfully but the error event 8193 and warning event 40961 generates right at the backup time as shown in message below, can someone please help me why am i getting this error while the backup are successful.

"Volume Shadow Copy Service error: Unexpected error calling routine IVssAsrWriterBackup::GetDiskComponents. hr = 0x80042302, A Volume Shadow Copy Service component encountered an unexpected error."