2020-09-14 16:31:48:WARNING: Writer System Writer has failure state VSS_WS_FAILED_AT_FREEZE with error VSS_E_WRITERERROR_TIMEOUT. UrBackup will continue with the backup but the associated data may not be consistent.
2020-09-14 16:31:48: WARNING: Writer ASR Writer has failure state VSS_WS_FAILED_AT_FREEZE with error VSS_E_WRITERERROR_TIMEOUT. UrBackup will continue with the backup but the associated data may not be consistent.
2020-09-14 16:31:48: WARNING: Writer Shadow Copy Optimization Writer has failure state VSS_WS_FAILED_AT_FREEZE with error VSS_E_WRITERERROR_TIMEOUT. UrBackup will continue with the backup but the associated data may not be consistent.
2020-09-14 16:31:48: WARNING: Writer Registry Writer has failure state VSS_WS_FAILED_AT_FREEZE with error VSS_E_WRITERERROR_TIMEOUT. UrBackup will continue with the backup but the associated data may not be consistent.
2020-09-14 16:31:48: WARNING: Writer IIS Config Writer has failure state VSS_WS_FAILED_AT_FREEZE with error VSS_E_WRITERERROR_TIMEOUT. UrBackup will continue with the backup but the associated data may not be consistent.
2020-09-14 16:31:48: WARNING: Writer WMI Writer has failure state VSS_WS_FAILED_AT_FREEZE with error VSS_E_WRITERERROR_TIMEOUT. UrBackup will continue with the backup but the associated data may not be consistent.
2020-09-14 16:31:48: WARNING: Writer COM+ REGDB Writer has failure state VSS_WS_FAILED_AT_FREEZE with error VSS_E_WRITERERROR_TIMEOUT. UrBackup will continue with the backup but the associated data may not be consistent.
The problem at the client (Volume Shadow Copy Service issues).
I had this errors and fixed them with VSS Doctor (Free tool for diagnosing and repairing Volume Shadow Copy Service issues).
Also I used this script: Fix VSS Writers 64