hi, we have issue with robot UR5 CB3, currently when we start on. the pendant showing that "incorrect robot mounting detected" even thought we had set the mounting with correct position, but still the robot start in "Idle" mode. we do some action such as rebooting the robot, plug unplug the cable. but still same. 
need ur help for how to solve this issue. thanks 

One cause of this that we have seen is bolts that are too long in the tool flange. If the bolts are too long they will push on the accelerometer and cause the robot to think that it’s mounted differently than how it’s specified in the installation file. 

its weird,and its happen suddenly during running production and robot hit something then we do restart the controller as usually. then comes error "incorrect robot mounting" even thought we don't move or take out the robot. now we just change the tool mounting bracket and its ok.

Yep, that’s exactly what we have seen. The only thing we’ve ever found, at UR’s direction, was the screws were too long and pressing on the bottom of the screw hole which happens to be where the accelerometer they use for detecting mounting is located causing it to read wrong

Hi Matthew - I am having the same issue with robot mounting although I currently have no screws in the tool flange and the error is still persisting.
Would you have any other advice?

If you had screws that were too long they could have deformed the plate where the accelerometer is mounted causing it to continue to read erroneously even after the screws are removed. The only remedy we’ve heard from UR is to replace the tool flange. It’s possible if you have a way to send dashboard commands to release the brakes from the dashboard server even with that error. You would send the brake release command to port 29999. I can’t remember off the top of my head the exact message but you can find it on the UR support site if you search for dashboard server.