Symptoms
You are backing up data of a Windows machine using file-level or disk-level backup plan.
In a while, backup fails with an error stack containing messages similar to the following:
Error code: 1012; Module: 20
LineInfo: 0xC523D9A02D03D55C
Fields: {"Query":"SELECT * FROM Win32_OperatingSystem","$module":"mms_vsa64_3917"}
Message: WMI 'ExecQuery' failed.
OR
Error code: 1012
Module: 20
LineInfo: 0xC523D9A02D03D55C
Fields: {"$module":"mms_vsa64_12420","Query":"SELECT * FROM Win32_OperatingSystem"}
Message: WMI 'ExecQuery' failed for query '%ls'.
OR
A Windows Management Instrumentation (WMI) query has failed. The WMI repository may be corrupted or it works incorrectly.
Cause
WMI is Windows Management Instrumentation, Acronis uses its functionality on Windows machines to get information about disks, system and services.
The error indicates that Acronis Agent had attempted a query via WMI tools and WMI tools failed to process it.
This is often caused by WMI repository corruption in the Windows OS.
Solution
Diagnosis of WMI can be performed with a special Windows utility:
A general article on WMI troubleshooting: Microsoft Technet: WMI isn't working