Out of over 800 installations of NinjaRMM, we finally hit a bug. The agent install appears to have installed successfully (with no apparent error message), but the program is missing from Programs and Features nor was our icon appearing in the Task Bar Tray. Further, the machine never materialized in the Ninja console. Upon searching the event logs, we discovered the install was failing with Event ID 1603.
Further investigation appears that Windows Defender may be blocking the installation. Regardless, the fix is to simply install the program via the command line.
It is very easy to install the NinjaRMM agent via the Command Line. First, move the .MSI installer to the root of C:\ (or wherever you wish to browse to). Then, open the command prompt as Administrator. Type in msiexec /i “C:\nameofinstaller.msi” (be sure to replace the name of the installer with the name of the NinjaRMM agent MSI, and be sure to browse to the file’s location if you moved it outside of the root of C:\).
Simple as that; it worked, and the machine appeared in our console and the agent icon appeared in our Task Bar Tray.