Robot - Execution troubleshooting

Message too large to process

Description

Automations that process large volumes of data may fail due to the following error: "Message: Could not retrieve the result of the job execution. This might be because a message was too large to process. Exception Type: System.Exception".

Potential issue

The data produced by the automation exceeds the value of the maxMessageSizeInMegabytes parameter in the uipath.config file.

Solution

Configure the automation to save the output in a Storage Bucket in Orchestrator or in Data Service, rather than using an output argument.

Unattended automations using UIAutomation activities do not work

Description

Unattended automations using UIAutomation activities do not work.

Potential issue

When a program such as Server Manager, set to start up automatically, shows a Windows User Account Control (UAC) prompt, it prevents the Robot from interacting with the user interface.

Solution

Identify the program that triggers the User Account Control (UAC) prompt and configure it so that it does not start up automatically.

Robot fails to start execution

Description

The Robot fails to start the execution of an automation and displays the following error: "Executor start process failed, reason System.Runtime.InteropServices.COMException: A specified logon session does not exist. It may already have been terminated.".

The following tables summarizes several issues and their solutions.

Potential issue	Solution
The Robot machine does not have enough resources (such as CPU, RAM, or Disk Space), so the Robot Executor is unable to start the automation.	Make sure that the Robot machine has enough resources (such as CPU, RAM, or Disk Space). Check the connection time by using the `mstsc` command-line function. It needs to be greater than 60 seconds, otherwise the error is displayed.
The logon session cannot be created at the moment. This can happen in the following situations: The Login to Console property is set to True for high-density (HD) robots. In this case, the Robot Service attaches itself to the current console session. This is not recommended for HD Robots, because there can only be one active console session at a time. Multiple RDP sessions on desktop Windows versions (not Servers). Desktop Windows versions can only handle one RDP session at a time per machine, whereas Windows Server versions can handle multiple RDP sessions.	In this case, you need to perform one of the following: Set Login to Console to False. This means that the Robot Service initiates an RDP connection from the Robot machine onto itself and attaches to it. This is the recommended method for HD Robots. Check the Windows version, it needs to be Windows Server. Check if the Studio and Robot versions is greater than 2018.1.3. Increase the value of the `UIPATH_SESSION_TIMEOUT`system environment variable on your server. The default value is 60 seconds, which might be insufficient due to slow performance on some machines. Restart the Robot Service after modifying this variable. Check if your Remote Desktop License is active on the server. Check if the Robots are in the proper groups. Local users need to be in the same Remote Desktop group. Check if the username of your RDP connection to the Robot machine is the same as the configured one. To avoid this error, sign off all the RDP connections on the Robot machine.

Potential issue

Solution

The Robot machine does not have enough resources (such as CPU, RAM, or Disk Space), so the Robot Executor is unable to start the automation.

Make sure that the Robot machine has enough resources (such as CPU, RAM, or Disk Space).
Check the connection time by using the mstsc command-line function. It needs to be greater than 60 seconds, otherwise the error is displayed.

The logon session cannot be created at the moment. This can happen in the following situations:

The Login to Console property is set to True for high-density (HD) robots. In this case, the Robot Service attaches itself to the current console session. This is not recommended for HD Robots, because there can only be one active console session at a time.
Multiple RDP sessions on desktop Windows versions (not Servers). Desktop Windows versions can only handle one RDP session at a time per machine, whereas Windows Server versions can handle multiple RDP sessions.

In this case, you need to perform one of the following:

Set Login to Console to False. This means that the Robot Service initiates an RDP connection from the Robot machine onto itself and attaches to it. This is the recommended method for HD Robots.
Check the Windows version, it needs to be Windows Server.
Check if the Studio and Robot versions is greater than 2018.1.3.
Increase the value of the UIPATH_SESSION_TIMEOUTsystem environment variable on your server. The default value is 60 seconds, which might be insufficient due to slow performance on some machines. Restart the Robot Service after modifying this variable.
Check if your Remote Desktop License is active on the server.
Check if the Robots are in the proper groups. Local users need to be in the same Remote Desktop group.
Check if the username of your RDP connection to the Robot machine is the same as the configured one. To avoid this error, sign off all the RDP connections on the Robot machine.

Password not provided

Description

Starting an automation from Orchestrator or Assistant displays the following error message: "Executor start process failed, reason System.UnauthorizedAccessException: Access is denied.".

The following table summarizes the potential issues and their solutions:

Potential issue	Solution
The Robot account was created without a password.	Edit the robot account in Orchestrator and provide the following values: Domain\Username* - The username used to connect to the machine on which the Robot is installed. If the user is under a domain, you are required to also specify it in a `DOMAIN\UserName` format. Password - The Windows login password.
The Robot Service is inactive.	Open the Services window. Select the `UiPathRobotSvc` service. Open the Properties panel for the selected service. On the Log On tab, select Local System account. Select Apply and OK to confirm the changes, then close the window. This ensures the Robot Service is running and has all the privileges it needs for executing automations.
The Robot machine no longer has administrator privileges.	Log in to the Robot machine with the same set of credentials with which you created the Robot in Orchestrator. If a process fails to start from the Assistant, then you need to contact your network administrator to allow admin rights for that user account.

System.Collections.IEnumerable cannot be serialized

Description

When using a Data Table in a Wait For Task and Resume activity, it returns the following error: "Exception: Type 'System.Collections.IEnumerable' cannot be serialized."

Potential issue

The DataRow object of Data Table cannot be serialized, so it cannot be persisted, leading to potential issues or errors.

Solution

Execute the Create Form Task activity and build the output by looping through data rows, to create a list of task objects. Then, loop through the output list of task objects using the Parallel For Each or For Each activities. In these loops, execute the Wait for Task and Resume activity for each task object.

Job stopped with an unexpected exit code

Description

Your job execution fails and the following error message is logged in Orchestrator: "Job stopped with an unexpected exit code: 0x40010004".

Potential issue

Commonly, this error occurs when:

The user account, used by the Robot, is forcibly logged off during the execution of the process.
The machine on which the Robot is running is manually shut down or restarted during the process execution.

Solution

To avoid this error, make sure the Robot is installed correctly for the intended type of automation: attended or unattended. Having the Robot installed in User Mode cannot execute unattended automations.

Additionally, configure the Robot session to suit your environment and business needs.

Execution troubleshooting

Message too large to process

Description

Potential issue

Solution

Unattended automations using UIAutomation activities do not work

Description

Potential issue

Solution

Robot fails to start execution

Description

Password not provided

Description

System.Collections.IEnumerable cannot be serialized

Description

Potential issue

Solution

Job stopped with an unexpected exit code

Description

Potential issue

Solution

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