SIRIS, ALTO and NAS: Failed screenshot with screen showing "(file) is missing or corrupt" or "BOOTMGR is missing"



This article describes the cause, and possible solutions for the screenshot verification errors, "(file) is missing or corrupt," or, "BOOTMGR is missing."


  • Datto SIRIS
  • Datto ALTO


These errors can have multiple causes, You may need to run a differential merge backup to reconcile the current backup with a new full scan of the target machine.

Figure 1: BOOTMGR is missing error 

Figure 2: BOOTMGR is missing or corrupt error 


Manually force a differential merge for the agent.  Running a differential merge forces the agent to check the entirety of each volume being backed up. A differential merge takes as long to run as a full backup, but only uses the storage space of a normal incremental backup. diffmerge.png

 Figure 3: Force a Differential Merge

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