Ctrl + Space is not working in a terminal after installing Cinnamon

Cinnamon is closely related to GNOME, and there Control + Space is commonly used to switch between key maps for different languages, like US and French.

Take a look at the keyboard setup. There should be a section with a large count of special keyboard options. Somewhere there you can choose another hotkey instead of Control + Space to switch keyboard maps/languages.

If you use just one language, you may just deactivate the function.

The following directions are based on plain GNOME, but it will probably work for Cinnamon too:

The current default virtual keyboard app for GNOME runs at startup and captures Control + Space.

Steps to fix:

• Right-click the keyboard icon in the GNOME bar.
• Select Configure → Global Config.
• Change Trigger Input Method from Control + Space.

From this answer https://stackoverflow.com/a/18924670/3405122

Another possible explanation is Ubuntu bug #1278569. To fix: ibus-setup