When an upgrade is being made using Deployment Wizard, the deployment job ends with error "Error irrecuperable durante la instalación" (translated as "Fatal error during installation"):
This error message is not an ITCM error, but is what the target OS returned when it tried to run the Agent installation package. This means that the package has a problem within its code which is the reason why it's failing.
Client Automation 14.0 and above
Under certain circumstances, when ITCM's ISO is copied or moved, there may be problems with the files in it. In order to solve this, it's recommended to download again the ISO (verifying md5 value) and load again the needed packages into Infrastructure Deployment Wizard using 'dsmpush' tool, as explained here: