Universal Robots Forum

Downgrade robot software to a version older than the original


From a previous post of @jbm I know that “The robot can only be downgraded to the original software version it was delivered with. Not further back from there, as there can be hardware or firmware changes that are “unknown” to an earlier software.”

However, is it possible to check if there are really hardware or firmware changes in one specific robot (by serial numer) that are unknown to that specific software version we want to downgrade to? We are experiencing strange behaviour randomly on some CB robots with Polyscope versions 3.13 and 3.14 and want to test if a software downgrade to 3.12 or 3.11 could solve the issue. (We assume the originally installed version was 3.13 and not earlier.)

Thanks for any suggestions,

1 Like


can you elaborate on what behaviour you encounter? we had to downgrade our 2 UR10 CB3 to 3.11. I see now that i already commented on your post regarding the same issue here C4A1: Communication with controller lost on CB3.0 robot

We have had no news from UR regarding that issue and are still stuck on 3.11 since then, are you in touch with UR to track down that issue? we raised the issue with our local distributor and here on the forum but it seems the issue has been lost, even with multiple users complaining about it.

If anybody at UR can check the internal status of that we would be very grateful as we have currently forbid our UR10s of being used for certain critical applications because of that.


Hi Thibault,
We are experiencing sudden termination of move commands randomly.
See here: Thread crashing in movej
Most often our thread disappears without any reason, while still performing a move. Sometimes the move command does not return at all, making the program freeze.
There are no C4A1 issues any more; here we measured and stress-tested the most time-consuming functions get_inverse_kin, is_within_safety_limits, and get_inverse_kin_has_solution, and added the required amount of sleep() depending on the robot model.


Thanks for the details, alright. We have seen the C4A1 error and crashes while jogging manually the robots, doesnt happen otherwise. I’ll be following if you find any resolution, might be related.