L3 - Default Environment (Required on creation):
Tested with process and form packaged in a process application. Edit: The issue is related to start forms.
Description (Required on creation; please attach any relevant screenshots, stacktraces, log files, etc. to the ticket):
Steps to reproduce (Required on creation):
- Build the Java process application from the get started guide with 7.18.0-alpha6 version: https://github.com/camunda/camunda-get-started-java
- Deploy on Tomcat
- Start the Loan Approval process
Observed Behavior (Required on creation):
The start form cannot be loaded and it's displayed:
Form failure: can't convert null to object
Expected behavior (Required on creation):
The form is displayed as described in https://docs.camunda.org/get-started/java-process-app/forms/#re-build-and-deploy
Root Cause (Required on prioritization):
The root cause is that the variables variable is not initialized in case of start event forms and it causes a frontend exception in https://github.com/camunda/camunda-bpm-platform/blob/master/webapps/ui/tasklist/client/scripts/form/directives/cam-tasklist-form-camunda.js#L101
In case of start event forms there is no taskId so the loadVariables call is skipped and variables remains uninitialized.
Solution Ideas (Optional):
Either initialize variables to empty array or add null checks everywhere where it's used.
The error can also be reproduced by deploying the three form and BPMN files attached to the ticket to a distro and start a process instance.