Can’t reconstruct with FBP_CUDA and SIRT_CUDA

These algorithms have 2 requirements:

  • Having a CUDA-compatible graphics card (GPU)

  • Having the CUDA Runtime 10.2 libraries installed

Having a CUDA-compatible graphics card

Please check that your GPU is on the list of compatible GPUs

Having the CUDA Runtime 10.2 libraries installed

Please install the CUDA Runtime version 10.2 binaries from

Reinstalling CUDA on Linux can be quickly done with this script

# uninstall nvidia driver and cuda driver
nvidia-uninstall && /usr/local/cuda/bin/cuda-uninstaller

# download the CUDA installer
wget ~/Downloads/

# install GPU driver and CUDA Toolkit from CLI silently
sudo bash ~/Downloads/ --silent --driver --toolkit

Specific Errors

SystemError: <built-in function connectSlotsByName> returned a result with an error set

This means that the PyQt package is missing or an old version (it must be newer than PyQt5==5.13.2)

Suggested Fix

Install PyQt5 and pyqtgraph with pip install pyqt5==5.15 pyqtgraph==0.12

qt.qpa.plugin: Could not load the Qt platform plugin “xcb” in “” even though it was found.

This might mean some system libraries are missing

Suggested Fix

Try installing apt install libxcb-xinerama0

qt.qpa.xcb: could not connect to display…

Missing DISPLAY variable. This means the application cannot find the display to show itself on.

Suggested Fix

You can set this via export DISPLAY=:N where :N should be the number of your display.