Unattended Job fails with UiPath.System.Activities assembly error

[daniel.h (Daniel Hess)]

Hi all,

we’ve encountered an error that we can’t explain or resolve.

Our setup:

• Orchestrator: 2024.10.1 (on-prem)
• Studio & Robots: 2025.10.1

We published a new RPA process to our Orchestrator. The process runs fine locally and via remote debugging. However, when starting it unattended, we get the following error:

System.IO.FileNotFoundException: Could not load file or assembly ‘UiPath.System.Activities, Version=25.10.3.0, Culture=neutral, PublicKeyToken=null’. Das System kann die angegebene Datei nicht finden.

The library UiPath.System.Activities v25.10.3.0 is available in Orchestrator, and when checking the Robot machine, the package seems to be successfully downloaded (also cleared the .nuget cache)

I found this topic (Issue with 2023.4.0: Unable to run code on robot machine: "Could not load file or assembly 'UiPath.System.Activities, Version=23.4.2.0" - #12 by Anil_G). Sounds similar, but didn’t help.

The deps in .nuspec file:

    <dependencies>
      <group targetFramework="net8.0-windows7.0">
        <dependency id="UiPath.ActiveDirectoryDomainServices.Activities" version="[1.7.1]" />
        <dependency id="UiPath.Excel.Activities" version="[3.0.1]" />
        <dependency id="UiPath.Mail.Activities" version="[2.4.10]" />
        <dependency id="UiPath.System.Activities.Runtime" version="[25.10.3]" />
        <dependency id="UiPath.UIAutomation.Activities.Runtime" version="[25.10.19]" />
      </group>
    </dependencies>

Any help or hints would be greatly appreciated!

Orchestrator Libraries:

[MohammedShabbir (ImYourUiPathAgent)]

The packages will be downloaded in this location C:\Users<Username>\.nuget\packages

As workaround please go to this location in your dev and copy the required package and then go to your robot machine and paste it there in the same location

And looks like the packages are not being downloaded on robot machine there can be multiple reasons like firewall blocks or package feed not accessible etc

[ashokkarale]

@daniel.h

Try clearing the NuGet Cache from the unattended robot user profile. It’s located normally at this location - %USERPROFILE%\.nuget\packages

[daniel.h (Daniel Hess)]

Our robots are using a shared NugetCache (each process has it’s own tech.user) to save some space.

UiPath.config includes this key:

  <packageSettings>
	<add key="packagesInstallationFolder" value="C:\UIPathNugetCache" />
  </packageSettings>

Deactivated it, cleared it - same problem.
Also copied manually the local package to the robot client - same problem.

[MohammedShabbir (ImYourUiPathAgent)]

@daniel.h

UiPath.System.Activities

Can you share a screenshot of project.json before you publish the package.

[daniel.h (Daniel Hess)]

Sure

here’s the project.json

{
  "name": "0551_Dispatcher",
  "projectId": "XXX",
  "description": "0551_Dispatcher",
  "main": "Main.xaml",
  "dependencies": {
    "UiPath.ActiveDirectoryDomainServices.Activities": "[1.7.1]",
    "UiPath.Excel.Activities": "[3.0.1]",
    "UiPath.Mail.Activities": "[2.4.10]",
    "UiPath.System.Activities": "[25.10.3]",
    "UiPath.UIAutomation.Activities": "[25.10.19]"
  },
  "webServices": [],
  "entitiesStores": [],
  "schemaVersion": "4.0",
  "studioVersion": "21.10.3.0",
  "projectVersion": "1.0.26",
  "runtimeOptions": {
    "autoDispose": false,
    "netFrameworkLazyLoading": false,
    "isPausable": true,
    "isAttended": false,
    "requiresUserInteraction": true,
    "supportsPersistence": false,
    "workflowSerialization": "DataContract",
    "excludedLoggedData": [
      "Private:*",
      "*password*"
    ],
    "executionType": "Workflow",
    "readyForPiP": false,
    "startsInPiP": false,
    "mustRestoreAllDependencies": true,
    "pipType": "ChildSession"
  },
  "designOptions": {
    "projectProfile": "Developement",
    "outputType": "Process",
    "libraryOptions": {
      "privateWorkflows": []
    },
    "processOptions": {
      "ignoredFiles": []
    },
    "fileInfoCollection": [],
    "saveToCloud": false
  },
  "expressionLanguage": "VisualBasic",
  "entryPoints": [
    {
      "filePath": "Main.xaml",
      "uniqueId": "XXX",
      "input": [],
      "output": []
    }
  ],
  "isTemplate": false,
  "templateProjectData": {},
  "publishData": {},
  "targetFramework": "Windows"
}

[Jon_Smith]

My gut would have said its related to a mismatch in the Studio / Robot version, as it sometimes gives a misleading message like that when the package isn’t compatible, but if you remote debugged on the same robot that ran it, then it should work fine.

Can you benchmark an empty process with just the System Activities package version, see if it can run?

[daniel.h (Daniel Hess)]

studio and robot are both 2025.10.1
i guess the studio version in the json file is old and never got updated.

Gave it a try with a new “clean” process with

 "UiPath.System.Activities": "[25.10.3]",

runs fine. unattended, same client

So… cleaning up (hints?) or rebuild the project?

test process project.json

{
“name”: “Activity_Test”,
“projectId”: “f46c51f1-5a79-41c0-925b-7e43264cc42f”,
“description”: “Blank Process”,
“main”: “Main.xaml”,
“dependencies”: {
“UiPath.System.Activities”: “[25.10.3]”,
“UiPath.UIAutomation.Activities”: “[25.10.19]”
},
“webServices”: ,
“entitiesStores”: ,
“schemaVersion”: “4.0”,
“studioVersion”: “25.10.1.0”,
“projectVersion”: “1.0.2”,
“runtimeOptions”: {
“autoDispose”: false,
“netFrameworkLazyLoading”: false,
“isPausable”: true,
“isAttended”: false,
“requiresUserInteraction”: true,
“supportsPersistence”: false,
“workflowSerialization”: “NewtonsoftJson”,
“excludedLoggedData”: [
“Private:*”,
“password”
],
“executionType”: “Workflow”,
“readyForPiP”: false,
“startsInPiP”: false,
“mustRestoreAllDependencies”: true,
“pipType”: “ChildSession”
},
“designOptions”: {
“projectProfile”: “Developement”,
“outputType”: “Process”,
“libraryOptions”: {
“privateWorkflows”:
},
“processOptions”: {
“ignoredFiles”:
},
“fileInfoCollection”: ,
“saveToCloud”: false
},
“expressionLanguage”: “VisualBasic”,
“entryPoints”: [
{
“filePath”: “Main.xaml”,
“uniqueId”: “2248919e-3885-4d7c-b4a0-d5c87e2d155f”,
“input”: ,
“output”:
}
],
“isTemplate”: false,
“templateProjectData”: {},
“publishData”: {},
“targetFramework”: “Windows”
}

[MohammedShabbir (ImYourUiPathAgent)]

Studio builds using System.Activities, whereas Robot executes using System.Activities.Runtime

Can you remove the Runtime packages and use the same packages as in your project.json. Rebuild the project, then publish..

After rebuild you can test it.

[Jon_Smith]

Ok, thats good then, shows that it can infact find the dependency and that error is a red herring.

How was the project built into a nuget package before uploading to the Orchestrator?
Its indeed odd your json states a Studio version of 21.10.3

[daniel.h (Daniel Hess)]

i publish directly form Studio to our orchestrator.

@MohammedShabbir:
In my Studio Project, i’m using System.Activities Package. When i publish it and download it from orchestrator afterwards. I see the .nuspect in the nuget contains the System.Activities.Runtime instead of System.Activities
So what exactly could i try?

btw same difference with the working test process.

I compared both and one difference i see (left - working || right - causes Error)

[Jon_Smith]

Ok cool, so no weird pipeline things.

I’d suggest adding all the dependencies from the problem process to the test one. See if it still runs. If it still runs once they are all in, then that will help eliminate some other potential issues.

[MohammedShabbir (ImYourUiPathAgent)]

Can you just create a new process with Ssytem.activities package. publish and test it.

If it works fine, then in your project we remove packge, save project, then install frsh package in code, and then test agian.

[daniel.h (Daniel Hess)]

OK problem found - or at least a fix.

you couldn’t see it - we use a custom libary for a custom logging activities.
It has also a dependency to System.Activities [but v.23.10.4]
Updated it to 25.10.3 - it works.

And i removed it for privacy reasons when sharing the json file

Still interesting, other processes, with newer System.Activities then 23.10.4 and with the custom libary, have no problems.
And i don’t understand why its working with remote debugging and telling me “Package not found” when unattanded.

[Jon_Smith]

Hard to know for sure, but I was hoping you’d deduce a conflict in dependencies like this. I agree strange that it runs on the other methods, something must get different with the full compile and packaging that causes a conflict between those versions.

For my own curiosity (I have made custom logging activities in the Marketplace), what custom logging is it for / what kind of custom logging does it do?

[daniel.h (Daniel Hess)]

Now, while knowing what causes the problem, i will deep dive into it when i find some time.

it’s just collecting some process informations and adds them to a central que. Another process transmits those queitems to different Databases like our KPI Dashboard.