Intermittent "HTTP 403 – Forbidden" error while trying to browse to a SharePoint web app

Intermittent "HTTP 403 – Forbidden" error while trying to browse to a SharePoint web app

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Consider a scenario where you receive the following error when you browse to a SharePoint web app

The website declined to show this webpage
HTTP 403 
Most likely causes:
This website requires you to log in.


This issue is intermittent. Strangely, if we create a copy of the web.config file, rename the web.config file, refresh the home page, we receive an "HTTP 404 - Page Not Found" error. Rename the web.config file back and refresh the page. The site is browse able for a while before failing after some time

We see the following error in Failed Request Tracing


A procmon trace captured while accessing the web app from the server showed the following:

w3wp.exe 4180 CreateFile C:\inetpub\wwwroot\wss\VirtualDirectories\Web80.Contoso.com80\bin ACCESS DENIED Desired Access: Read Data/List Directory, Synchronize, Disposition: Open, Options: Directory, Synchronous IO Non-Alert, Attributes: n/a, ShareMode: Read, Write, Delete, AllocationSize: n/a, Impersonating: NT AUTHORITY\IUSR


This issue usually occurs when a request from an authenticated user without local admin rights results in a failed read of the /BIN directory by the impersonating w3wp.exe (IIS worker process for ASP.NET) process. This behavior is typically associated with lack of permissions to the temporary folder /BIN where ASP.Net assemblies are Just In Time (JIT) compiled.


The solution is to ensure that the Authenticated Users or <SERVER NAME>\Users group (which usually contains DOMAIN\Users group) has Read & Execute, List Folder Contents and Read permissions on the /BIN folder below C:\inetpub\wwwroot\wss\VirtualDirectories\{Sitename80}. Follow the steps listed below to grant the required permissions:

  • Open Windows Explorer and navigate to the /bin directory of your web application
  • Right-click on the folder and click on Properties
  • Go to Security tab and click on Edit
  • Click on Add and add the local server group Authenticated Users or <SERVER NAME>\Users (this usually contains DOMAIN\Users group).
  • Select the Read & Execute, List Folder Contents and Read permissions (if you are planning to add Everyone to the /bin folder, grant Read permissions only)
  • Click OK to apply the new settings

Refresh the page and we should be able to browse to the site.

There are instances where this permission needs to be re-applied as part of every deployment and we may often find that the permissions have reset after touching the Authentication Providers settings in Central Admin.

More Information

If an administrator accesses the site/feature that caused the error, the subsequent requests from non-administrators would succeed. This behavior is typically associated with lack of permissions to the temporary folder where ASP.Net assemblies are Just In Time compiled.

The freb trace shows a 403.0 for ManagedPipelineHandler

It seems to go through quite a few ASPNet events - but happens during the ASPNetPageRender - it goes to the ASPNetPageRender Enter, then ASPNetHTTPHandler Leave.Only then does it get a 403.0 which is not an official RFC error. The first sub-status for 403 is 403.0.

Application pool in Classic or Integrated mode

  1. Application Pool in Classic Mode – In this case, we can configure a Wildcard mapping for ASPNET_ISAPI.dll at the website level. That would propagate to child virtual directories. That should not need any further modifications at the virtual directory level.
  2. Application Pool in Integrated Mode – In this case, all relevant virtual directories would need individual modifications. They need to be set for specific handler. E.g. ‘book’ virtual directory needs mapping for BookAPI and ‘movie’ directory would need mapping for MovieAPI.
  • Hi Praveen,

    Thank you so much for your article. We experienced similar situation that sometimes the clients received 403 Forbidden. We will try to give Read permission to the Bin directory.

    My question is, how about the client is anonymous? In our SharePoint, we have enabled the Anonymous permission. Should we give read access to Everyone?

    Thank you in advance


  • Hi Praveen,

    I am getting HTTP 403 Forbidden for /_vti_bin/client.svc and all. .svc files under /_vti_bin. Initially I was not able to browse the /_vti_bin folder itself, however I was able to resolve it by enabling Directory Browsing. But I am still unable to browse client.svc. I took Failed Request Tracing log and below is the error:


    ModuleName : ManagedPipelineHandler


    HttpStatus : 403

    HttpReason : Forbidden

    HttpSubStatus : 0

    ErrorCode : The operation completed successfully.


    Any suggestions on how to resolve this...

  • Exactly what I needed.  Worked great, thanks!

  • hi Fuady,

    Yes. By default, Everyone has Read access to the folder. But if its missing, then please grant the permissions.

    - Praveen

  • hi Bhavik,

    Could you check if 'domain\users' is added to the ISAPI folder under 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15' ?

  • Great Post, it helps me to fix my problem also!

  • This is great. My problem is resolved.

  • This is great. My problem is resolved.

  • Found similar behavior post-deploy of SP1, and used this reference to guide on the troubleshooting. Effectively found the lack of ACLs in the bin directory and solved it... thanks Praveen!

  • That worked for me too.

  • thanks mate. worked for me. one thing to keep in mind - it may not work if you add those permissions to folder which higher in the hierarchy.

  • [SOLVED] I had 403 on WFEs, but all worked fine from workstations. Solution: turn off the proxy on WFE.

  • HI All,

    we have similar experience on few of the links resulting in 403 error . we have 4 WFE servers in SP Farm and the functionality is working perfectly fine on one of the servers whereas we are having issue on rest of 3 WFE servers.

    we have tried the above recommendations but no luck yet.
    enabled request tracing logs and getting the below warning in ISAPI module.

    ModuleName IsapiModule
    Notification 128
    HttpStatus 403
    HttpReason Forbidden
    HttpSubStatus 0
    ErrorCode 0
    ErrorCode The operation completed successfully. (0x0)
    can you please recommend and share your viewpoints on priority.

  • You, sir are a boss! Thanks for this solution.

  • Thanks! saved me from hours of binging :)

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