Could not load file or assembly 'UiPath.Web.Activities, Version=, Culture=neutral, PublicKeyToken=null'


I am recieving this error in Orchestrator, when trying to run a robot.
If I downgrade the UiPath.WebAPI.Activities to 1.18.0 the problem dissappears.’

Could not load file or assembly ‘UiPath.Web.Activities, Version=, Culture=neutral, PublicKeyToken=null’.


Hi @SorenB

Please upgrade the version to the latest one and keep the runtime rule as lowest as applicable and it will work!!

manage packages → project dependencies → update all the packages to the latest version and keep the lowest applicable version for the runtime rule.


It already states that.

low rule

Hi @SorenB

Have you tried for all the dependencies?


All dependencies are listed with “Lowest Applicable Version”.


This could happen due to UiPath Studio version and package compatibility. What’s the version of your Studio?

Ashok :slight_smile:

The machine running the automation is 23.4.1


Close the Studio. Try deleting the packages from .Nuget folder. Path would be like this.

Once deleted the API packages, Start the studio, it will ask to restore the package. Install it and this should be resolved.

Ashok :slight_smile:

The error message “Could not load file or assembly ‘UiPath.Web.Activities, Version=, Culture=neutral, PublicKeyToken=null’” indicates that Orchestrator cannot find the expected version of the UiPath.Web.Activities package (version while running your robot. This is likely because you’ve downgraded the UiPath.WebAPI.Activities package in your project, but the robot still has a dependency on the older UiPath.Web.Activities package (version

1. Update the Robot Dependency (Recommended):

Since your robot is working with the downgraded UiPath.WebAPI.Activities package (version 1.18.0), it’s best to update the robot’s dependency to match.

2.Verify Compatibility (Important):

After making any package version changes, ensure compatibility between the UiPath.WebAPI.Activities and UiPath.Web.Activities versions. Refer to UiPath documentation for compatibility information to avoid future conflicts.

3. Delete the all packages and reinstall all of them one by one:

If updating UiPath.Web.Activities isn’t feasible due to dependencies in your robot, you might consider upgrading the UiPath.WebAPI.Activities package back to version (less recommended as it deviates from your current working setup).

Note: pls take a backup of your project and reperform the steps, also check your UiPath version with Orchestrator version

Now I am getting this error shown below.

Why does it say that nearest version found in “Official” package source is “1.19.0-preview”, when I clearly am able to find and install version “1.20.1” - is this a bug???