This article is a collection of issues which come up frequently.

Dataflows are not found #

Dataflow queries which do not give a result are usually caused by a forgotten call to run.ossdataflow.

NOTE: As of Joern v1.1.299, it is no longer necessary to call run.ossdataflow explicitly. This is done as an automatic step during CPG creation.

No suitable CPG generator found for: <source_path> #

There are 3 possible explanations for this error:

The <source_path> provided is invalid: #

Confirm that the <source_path> provided exists. To do this, execute the following command from the same directory from which you started Joern:

ls <source_path>

The language isn’t supported #

You can run joern-scan --list-languages to get a list of all the languages supported by Joern/Ocular. If the language you’re using does not appear on this list, then it definitely isn’t supported by Joern. If it does appear, then it may only be supported by Ocular.

Automatic language detection failed #

You can specify the language to use by running

joern-scan --language <language> # and other opts

for joern-scan, or with

joern> importCode.<language>(<path_to_src>)

in the Joern console.