Just a short warning to KDE Plasma users with NVIDIA drivers. Lately we have seen many crash reports from NVIDIA users who updated to version 384.xx. Affected is at least KWin and KScreenLocker, which means one cannot unlock the session any more. The crash happens in the NVIDIA driver triggered from somewhere in QtQuick, so completely outside of our code. A typical backtrace looks like that:

#0 0x00007fffdedffc02 in ?? () from /usr/lib/nvidia-384/libnvidia-glcore.so.384.69 #1 0x00007fffdf0ca9ba in ?? () from /usr/lib/nvidia-384/libnvidia-glcore.so.384.69 #2 0x00007fffdef953da in ?? () from /usr/lib/nvidia-384/libnvidia-glcore.so.384.69 #3 0x00007fffdefab2d4 in ?? () from /usr/lib/nvidia-384/libnvidia-glcore.so.384.69 #4 0x00007fffdef99bce in ?? () from /usr/lib/nvidia-384/libnvidia-glcore.so.384.69 #5 0x00007ffff5f0b681 in QSGBatchRenderer::Renderer::renderMergedBatch(QSGBatchRenderer::Batch const*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #6 0x00007ffff5f0bf8d in QSGBatchRenderer::Renderer::renderBatches() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #7 0x00007ffff5f11909 in QSGBatchRenderer::Renderer::render() () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #8 0x00007ffff5f0209f in QSGRenderer::renderScene(QSGBindable const&) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #9 0x00007ffff5f0257b in QSGRenderer::renderScene(unsigned int) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #10 0x00007ffff5f3dd2e in QSGDefaultRenderContext::renderNextFrame(QSGRenderer*, unsigned int) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #11 0x00007ffff5f97b04 in QQuickWindowPrivate::renderSceneGraph(QSize const&) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #12 0x00007ffff5f4715e in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #13 0x00007ffff5f4b8dc in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5 #14 0x00007ffff4e28989 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #15 0x00007ffff39966ba in start_thread (arg=0x7fffd4d5a700) at pthread_create.c:333 #16 0x00007ffff47353dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

I would recommend to not update to that driver and if you are affected to downgrade again.

Update

Together with NVIDIA we figured out the root problem causing the crash. The sandbox of the lockscreen introduced in Plasma 5.10 is too restrictive for the NVIDIA driver. We have now worked around the issue by removing parts of the sandbox when running on NVIDIA and released a Plasma 5.10.5.1 release. This should be shipped to distributions shortly. We will look into a way to make the sandbox work again also for NVIDIA users with Plasma 5.11.