Cannot launch rviz from the RI webshell

I am trying to start rviz using rosrun rviz rviz and am getting this error in the webshell

user:~$ rosrun rviz rviz
[ INFO] [1589178368.887611066]: rviz version 1.12.17
[ INFO] [1589178368.888653320]: compiled against Qt version 5.5.1
[ INFO] [1589178368.888680734]: compiled against OGRE version 1.9.0 (Ghadamon)
[ INFO] [1589178375.812034031, 224.314000000]: Stereo is NOT SUPPORTED
[ INFO] [1589178375.812399549, 224.314000000]: OpenGl version: 3 (GLSL 1.3).
QXcbConnection: XCB error: 2 (BadValue), sequence: 546, resource id: 400, major code: 130 (Unknown), minor code: 3

what do I need to do to get rviz to start?

This sometimes happend with RVIZ, it shoudl work if you start it again. Please check the graphycal tools icon and see if it appears there. If note please post here some mages showing the issue.