unregisters the external evaluator at location exec for system sys so that it is not used by ExternalEvaluate and related functions.


unregisters the external evaluator with the specified registration UUID.


  • UnregisterExternalEvaluator[sys,exec] effectively blocks the executable exec from being used by ExternalEvaluate.
  • exec is an executable file that can be used to execute code for the language or system sys.
  • exec can be specified as File[].
  • In UnregisterExternalEvaluator[sys,], possible choices of sys include:
  • "Python"Python
    "NodeJS"JavaScript running through Node.js


open allclose all

Basic Examples  (2)

Remove an evaluator so that ExternalEvaluate cannot find it:

Register the evaluator so it can be used:

Manually specifying unregistered evaluator installations also fails if the evaluator has been unregistered:

Register it again with RegisterExternalEvaluator, and now it is usable:

Scope  (1)

Get all installations and randomly choose one to be the preferred installation:

Unregister all installations except the preferred one:

Now all of the installations except the preferred are unregistered for use:

Introduced in 2017