Comment 26 for bug 833729

Nothing. Just delete that file if it exists before remotely logging in. If you are at a remote location, you can ssh into the machine to do this.

As I understand it, the reason is this:

Every time you log in, from a remote computer or on the local console, a test is performed to decide whether the display can support certain features of Unity. This test takes a few seconds, so someone decided to record the result by creating a file in /tmp, so that next time you log in it doesn't need to perform the test. So what happens is, you boot up your brand new installation for the first time and log in to the local console, the test runs and the result is recorded by creating /tmp/unity_support_test.0 Now, every time you log in unity assumes you have the features of a local console. You install xrdp or nx or whatever and then try a remote login. The functionality available is different and unity needs to fall back to a simpler version but it sees the file in /tmp and doesn't test so it tries to run as though you were a local console, and fails.

If you have deleted the file, then when you remotely log in the test will be performed and unity will see the different feature set and act appropriately. It will then create /tmp/unity_support_test.1 which means that if you later log in to the local console you won't get the right result, but remote logins will work OK.

Just to be clear, this workaround is for bug 889996. I believe 833729 is fixed.

I use nx nomachine to log in to my desk PC here at home from a windows machine at work successfully on a daily basis, so it does work.