Talk:ModuleNotFoundError

When you start gnuradio-companion or execute grcc, if the system isn't configured properly for GRC to find the GNU Radio Python scripts and/or libraries, then you will see an error message similar to this one:

If you get this error message, try changing your shell environment settings as per the instructions below to see if either changing the PYTHONPATH or LD_LIBRARY_PATH fixes the issue.

A. Mac OSX / macOS

See the MacInstall guide for issues and settings for OSX.

B. Determine your installation prefix

If you don't know or remember your installation prefix, perform the following step:

• on a terminal screen, enter gnuradio-config-info --prefix

then use that prefix in place of {PREFIX} in the following commands.

C. Finding the Python library

Using your file manager, look in {PREFIX}/lib for a directory to match your Python version. For example, python2.7 or python3.7; note the combination of python and the version as {major}.{minor}, which is used by all Python installs by default. Use that directory name in place of {PY-VERSION} in the following commands.

D. Setting PYTHONPATH

- For almost all Debian / Ubuntu (and derivative) systems, and most other 32-bit Unix/Linux systems, use:

export PYTHONPATH={PREFIX}/lib/{PY-VERSION}/dist-packages:{PREFIX}/lib/{PY-VERSION}/site-packages:$PYTHONPATH

- For other 64-bit systems, use:

export PYTHONPATH={PREFIX}/lib64/{PY-VERSION}/site-packages:$PYTHONPATH

E. Setting LD_LIBRARY_PATH

- For almost all Debian / Ubuntu (and derivative) systems, and most other 32-bit Unix/Linux systems, use:

export LD_LIBRARY_PATH={PREFIX}/lib:$LD_LIBRARY_PATH

- For other 64-bit systems, use:

export LD_LIBRARY_PATH={PREFIX}/lib64:$LD_LIBRARY_PATH

F. Store the commands in a Bash start-up file

Once you have determined the correct two export commands to use, open your text editor and put them in your ~/.profile or ~/.bash_aliases or ~/.bashrc file and restart your terminal.