This issue is caused by the snapshot path in the VM 's configuration being different from the actual path on a file system in terms of symbols capitalization. You can confirm this by comparing paths in bold in the Task.<VM NAME>.<VM UUID>.log file:
[22.01.2019 19:39:09] <28> Info [AP] (65e8) output: <snapshots>
[22.01.2019 19:39:09] <28> Info [AP] (65e8) output: <data_root type="string">C:\Temp\<VM name></data_root>
[22.01.2019 19:39:09] <28> Info [AP] (65e8) output: <list>
[22.01.2019 19:39:09] <28> Info [AP] (65e8) output: <size type="integer">0</size>
[22.01.2019 19:39:09] <28> Info [AP] (65e8) output: </list>
[22.01.2019 19:39:09] <28> Info [AP] (65e8) output: </snapshots>
[22.01.2019 19:39:09] <11> Info [AP] (65e8) command: 'file2text\n\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy16\temp\<VM NAME>\Snapshots\<VM UUID>.xml\n2097152\n'
[22.01.2019 19:39:10] <10> Info [ReconnectableSocket] Stop confirmation was sent on [c1d84e94-b09b-4039-a8dc-4973e12934fc].
[22.01.2019 19:39:10] <23> Error [AP] (65e8) error: The system cannot find the file specified.
[22.01.2019 19:39:10] <23> Error Failed to open file [\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy16\temp\<VM NAME>\Snapshots\<VM UUID>.xml] in readonly mode.