Error Execution failed with exit code [1603].Unable to install MIMECAST via SCCM -

Came across the error Execution failed with exit code [1603], while installing Mimecast for Outlook 7.10.1.133 (x86) via SCCM.

In the logs, it was only reporting – MimecastforOutlook7.10.1.133 Installation completed with exit code [1603].

Tried to install the app manually and at the verification step the installer was not able to detect the .Net Framework 4.5.2 (required for this version of MIMECAST)

Installer Screenshot after rectifying the issue.

Checked the .Net Framework on the machine, it was already installed.

Checked the Outlook installation on the machine, it was installed as required under path

C:\Program Files (x86)\Microsoft Office\Office15\
For Reference.

Issue – The installer was not able to find the path of outlook installation, thus it was not able to detect .Net Framework. It occurs when GPO leaves writing some registry entries. It blocks the installing of apps that are running on top of another app, in our case it was mimecast which runs as a pluggin on top of outlook.

Solution –

Checked the registry –

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\OUTLOOK.EXE
It is meant to have two string values - 
- Default
- Path
Refer to image below.