KB-1175 Processes fail with "Could not find variable ac!<variable>" error


Processes fail to execute at certain nodes after modifications with the following error:

Could not find the variable ac!<variable>


This happens when process models have been modified with new interfaces. Instances that have been started prior to the changes will still pick up these new interfaces even though the models are not set up as long as the interfaces are saved in the same name. For example, if you modify your old interface to have new values but don’t change the name of the interface, you will run into this problem.

The new interface will still be picked up by the inflight model and since the process doesn’t have the new activity class parameters, it will fail.


Care should be taken to see if making any changes will affect any in-flight models. If you intend for existing instances to pick up the changes, you will have to upgrade the model using the Process Management Services shared component. If you don’t want the existing instances to pick up the changes, modifications to objects should carry new names so as to only affect models that have not been started.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: March 2017