One of my backups gives error when all should be OK

Bruno, seeing the _v11.tib would suggest that there have been some issues where this or previous files were not able to be written successfully thus seeing _v2 - v3 etc upto v11.

Have you checked the actual files on the NAS to confirm that there are no such other vX files?

What happens if you try a Validation for this backup task?  Do you get error messages for any missing files?

Steve, this is set up as a Full backup with validation and with cleanup set to keep no more than 2 full versions. On the NAS, all looks perfect. The folder contains the two expected files ... C Drive_full_b10_s1_v1.tib and C Drive_full_b11_s1_v1.tib, and nothing else.

Validation is done on every backup and passes well.

What seems odd is that the failure only occurs when the task is started by schedule, but not when the task is run manually.

I checked the script file and see nothing amiss there. I also ran the Scheduler Manager and all appears OK there.

In checking past history, I did find that on 12/28/2017 two things happened. First is that I updated the machine from Windows 7 Pro to Windows 10 Pro. Second is that when the task ran that evening I manually stopped it. I can't remember why I did that, but it has been since that time that the failures have happened. No clue in there as to what that v11 thing is all about.

I think what I will do is clone the task and see if that fixes it.

If it were me I would ZAP the task and recreate it anew.  That would get rid if the bad task from the database and in turn fix the issue.

Update... I cloned the task. But the error still exists in the new task. I have now created a completely new task from scratch. Since by schedule it only runs twice a month, I will need to wait until March 8th to see if it succeeds by schedule.

I have some interesting new information.

This same problem has just appeared on my second machine... here is the fault in the log file.

2/27/2018 4:55:05 PM: -08:00 8656 I00640000: Writing full version to file: C Drive_full_b12_s1_v1.tib
2/27/2018 4:55:06 PM: -08:00 8656 E01E50023: Error 0x1e50023: Cannot access backup file \\NASBox\Acronis\Asus2\Disk Images\C Drive\C Drive_full_b12_s1_v11.tib. Please ensure that you entered the correct credentials for the network share.

This backup task does a full backup every time and keeps no more than two versions... same on both machines. It has worked just fine up until now. On my other machine, the problem started occurring when trying to create C Drive_full_v9_s1_v1. Oddly, the failure only happens when running the backup on schedule. Manually starting it works just fine.

As a programmer, I am now nearly convinced that there is a string handling problem in the program which has appended an extra "1" on the end of the file name. I will report it as a bug to Acronis as soon as I can figure out how to write it up.

Bruno, good spot if this is proved to be correct and the extra '1' is the bug here!

Hello BrunoC,

May I ask you to send us Acronis system report from the affected PC via Feedback along with a couple of screenshots showing your settings ans how the backup chain looks in the target directory? 

Thank you in advance! 

Hello Ekaterina,

I have already opened a support case. I just generated a system report and screen shots as you've requested and sent it via feedback. I hope it helps.

Further information...

As mentioned above on 2/23/2018, I created a completely new backup task on my wife's PC. It was configured just like the failing task but I changed the name of the backup so as to avoid file name issues. I created the first backup manually.

When it was time to run the next backup by schedule, it failed again. So I changed the task to use a different backup destination folder on the NAS and reset the schedule to start in a few minutes. It then succeeded to run on schedule. It is next scheduled to run in two weeks so we'll see what happens then.

I have provided the information to the team for the support case.