I get the above error. Effects were ok afterward. Intel graphic plasma 5.11 archlinux Is that the regression? I saw the same error in this forum before. The below is my post on the same problem in kde forums. https://forum.kde.org/viewtopic.php?f=111&t=142454
This is not a bug in our software. The driver reports an internal error condition and we restart compositing afterwards. Everything works as it should from our side. The issue is that the Intel driver triggers a graphics reset. But that's Intel's department.