Wait for Form Task and Resume - Error


This is the second time I meet this error in my workflow, and I wonder if many people have encounter it yet. Still, i’m unable to clearly understand the error, or to find a good solution.

Process is quite simple : I create a new Task and wait for it to be completed :


The problem occurs when the robot goes to the Wait for Fom Task and Resume.
Here is the following error :

  1. In the Assigns, I define several variables from a datatable.
    No errors here, datatable is quite simple and I just put severals assigns one under another one.

  2. A Task is created with the Create Form Task
    In the collection I put all the variables.
    No erros here, the task is perfectly created according to the task Editor and I see it on Orchestrator.

  3. Then the robot has to wait. The error occurs as soon as this activity begins.
    Reason is still unkown

Thank you for your help or any advices !

I dont want to be nosy here since i never used those activities, but as an experienced developer, when we need to keep data stalled for long period of time, even when process ends and no memory can be used, we serialize the objects (kind of as text) save to disk to be able to get it back when in need, so your message says you tried to do that to an object that has no support for it… Do you have anything related to email in your form data?

All variables within the same scope of ‘wait for task’ activity has to be serializable. please refer to https://docs.uipath.com/studio/docs/orchestration-process#section-best-practices for ways to achieve the same

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Best practice of building Orchestration Process would be to use persistence package activities (wait for task, wait for job etc) only in the main.xaml and move any bunch of steps/activities (like some UI automation activities), that does not have serializable input/output in a secondary workflow file (and use invoke workflow from main.xaml) .

This will ensure that we do not have non-serializable steps in the same scope as of ‘wait for task’ or ‘wait for job’ etc , because at these points, the workflow context is persisted so that workflow goes in to a suspended mode, freeing up the Robot.
Also, this makes main xaml to be more modular with activities that orchestrates multiple RPA workflows (through job or queue item) and human tasks.


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