Unable to open Orchestrator. Error "Could not load file or assembly System.Web.Mvc" 0x80131040

I have installed Orchestrator on IIS following all the pre-requisites mentioned. But after installation when I click on browse to open up the Orchestrator version I end up getting error and login/home page doesn’t show up. I modified the web.config to disable custom error and have detailed httperror. and below is what I get on the browser window.

Could not load file or assembly 'System.Web.Mvc, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. 
The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Kindly help!!!

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Hi @ParamjyothChadha
Check your .net framework , update the required one ,
Restart the IIS
“WebDeploy_amd64_en-US.msi” this need to be installed
Check “Microsoft Visual C++ 2015 Redistributable (x86) - 14.0.23026” or higher

Please let us know which version of Orchestrator you are installing, Version of Windows, and the method in which you installed Orchestrator and any prerequisites.

If it is 2019 or 2020 please make sure that .NET Framework >=4.7.2 is installed as Maneesha suggests. WebDeploy is not needed unless you are using a scripted install similar to the Azure installation.

Please check the install log if you passed the flag during installation to see if there are any errors.

Thanks @Maneesha_de_silva and @codemonkee for your response.

I am installing the orchestrator using the UiPathPlatformInstaller 20.4.1. I am doing an on-premise installation on a windows server 2016 and have followed the prerequisites from this link

The .Net framework is 4.7.2 and installed the ASP.NET Core Runtime 3.1.4 Hosting Bundle as well.

Today morning I performed a fresh installation, rolling back the previous one and now getting below exception

Any idea why this would be happening? This error get’s logged in Event Viewer and nothing shows up on the browser

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If the user is yet to login and make an existing session the following error is normal.

Abp.Authorization.AbpAuthorizationException: Current user did not login to the application!
   at UiPath.Orchestrator.Web.Common.Authorization.UiAuthorizationHelper.<AuthorizeAsync>d__3.MoveNext()


What do you have configured for authentication? If using the default configuration you should be greeted with a basic login form asking for username/email and password for the Default tenant.

The only active login would be the admin login which is set during installation.
With additional configuration you can setup Windows Authentication, SAML2, etc.

(Side note, I’ve only installed Orchestrator 2018.3 and 2019.10 using the Orchestrator MSI, but I assume not much has changed on the installation for 2020)

The blank page you are showing is that before or after you attempt to login?

I’m sure the community can help you solve the problem, but just in case you are under a deadline to get it up and running, I would reach out to UiPath’s Technical Support if needed.

Hi @codemonkee,

I have administrator access on the server, on which I am setting up the orchestrator. The Database is on a separate server on which I have admin access too.
During Orchestrator Installation :

  1. On Orchestrator Application Pool Settings, I have set up Custom Account entering my credentials and updated the Group Policy to include my username as part of ‘Log on as a batch job’ policy.
  2. On Orchestrator Database Settings, I enabled SQL Server Authentication and provided credential that has db_Creator access (created as part of pre-requisite steps)
  3. On Orchestrator Authentication Settings, I configured the default Host and Tenant password and enabled Windows Authentication.

Please let me know, if I have been wrong in performing any of the above steps.

Also, I am getting that blank page after I browse the Orchestrator from the IIS. I am not getting any login page.

Hi @ParamjyothChadha
When you received uipath logo on that browser means that almost connection of your one is ok, there may small things may be to correct you.

And check proxy, let bypass proxy(add your orchestrator name to proxcy) may be your company have network restrictions

This is quite a strange behavior, when I am trying to browse the newly installed Orchestrator from the server on which it got installed. It automatically tries to establish connection and authenticate the logged in user and fails, since the user is still not configured. But when I try to access the same Orchestrator from a different machine in same domain, it give me a login page and works perfectly fine.

I hope this issue , that I am getting on the web server can be ignored until Orchestrator is accessible and working perfect from other machine!

Thanks @Maneesha_de_silva and @codemonkee for your support. Really appreciate it!


Yes, that is another possibility. I will check with the IT folks on this as well. May be there are proxy restriction on the server.

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Yes , check with your network admin , will give you the issue sort out ,
Because this may your network policy and rules​:slightly_smiling_face::sunglasses:

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