If you use a Lenovo Thinkpad computer running Windows 10 you may experience a situation where the Alt Gr key stops working normally and just works as the regular Alt key.
Ctrl + Alt can be used as a substitute, but that’s only a workaround.
The problem seems to be related to the Synaptics Pointing Device driver.
The problem can be resolved for some time by reinstalling, rolling back or updating the Synaptics Pointing Device driver and then restarting the computer.
The problem can reappear after some weeks. However it can be resolved again by repeating the above steps.
If I discover a permanent fix, I will update the article again.
The driver can be rolled back this way:
1. Open Device Manager
2. Open Properties for Synaptics Pointing Device
3. Click: Rollback driver
4. Restart the computer.