Blank Output when running an agent

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When the input argument is more than 10000 characters, blank output is generated.

Issue Description

Agents that incorporate RPA workflows to generate output may exhibit inconsistent behavior between development and production environments. When executed in Studio Web (Agent Builder), the agent completes successfully with all expected outputs populated. However, when the same agent is deployed and executed using an unattended robot when invoking the RPA workflow tool call within a production environment, output files may be empty or blank, despite the process completing without errors.

This issue typically manifests in scenarios where:

  • An Agent utilizes an RPA workflow executor to generate substantial output data (such as HTML content, large text files, or extensive JSON responses)
  • The workflow output is passed to subsequent activities or saved to external storage locations
  • The agent functions correctly in Studio Web but fails to produce output when running with an unattended robot (an unattended license is used only for the RPA workflow tool call)

When the agent is deployed and executed, the output file is empty. Investigation may reveal that the output from the agent is not being passed as input to the RPA workflow and subsequent activities; instead, it appears to be attached under execution details rather than being processed as an argument.

Note: RPA workflow is also invoked as a tool call to generate the final output inside the agent.

Root Cause

The issue is caused by the RPA workflow executor version not supporting the offloading of input arguments.

Starting with this version, the robot supports input and output arguments with a length of more than 10,000 characters.

Resolution

There are two options to resolve this issue.

Option 1: Use Cloud Serverless Machines

  1. Switch the agent execution to use Cloud Serverless machines
    • Note: This option requires robot units to be available
  1. Configure the agent to use Cloud Serverless execution in Orchestrator

Option 2: Upgrade the Robot Version

  1. Upgrade the on-premise robot to version 25.10 or higher
  2. Download the UiPath Studio MSI installer
  3. Install the updated version on the machine running the unattended robot
  4. Restart the robot service after installation
  5. Re-deploy and test the agent