Summary:

When installing the Classic Outlook Plugin the installation process fails half way through with the following error message:

"Could not obtain user's interface language. Try again?"

Description 

Cause:

This was caused by some settings in Internet Explorer 11.

Resolution:

To get the Classic Outlook Plugin to install correctly do the following:

1. Add Sage CRM to "Trusted Websites" under Internet Options -> Security in IE11

2. Add the CRM URL to the Tools -> Compatibility View Settings section in IE11

More information:

To make sure there are no more issues during the installation process, make sure the user installing the Plugin is an admin user on the machine and also have firewall and antivirus disabled for the duration of the install as these may also cause issues.