At the end of the installation a messagebox is showed with an error 1755 , which refers to an error 1622. The installation however seems to have completed correctly. I believe the problem is related to installing an executable (Firebird-2.5.9.27139_0_x64.exe) which is installed via a custom action that runs a script that calls the following command: LaunchAppAndWait(supportDirPath + "\\Requirements\\Firebird-2.5.9.27139_0_x64.exe","/SP- /VERYSILENT",WAIT); The custom action is run in deferred mode with user context and no error is found in the installation log after the task is completed. If i disable the custom action there is no error, and therefore i think the error is linked to that action. The error occurs in all the PCs on which I tried the installation and therefore it is not linked to some configuration problem of a particular PC. Even launching setup with administrative rights does not solve the problem. I attach the log file. ... View more