Do you have a specific error message?
There should be a PHP error log somewhere on your server. The exact location depends on the server configuration.
Was this a direct upgrade from 2.8.4 to 3.0.1 without installing version 3.0.0?
(Iām not sure if that is relevant, though.)
turns out that Gallery snippet does not really like modx3 yet, and it writes its own media source path causing some sort of issue tthat prevents it from loading.