Getting 403 error in OnClientFileUploadFailed

[Kobi]

I am using the file upload feature and getting a 403 error in the OnClientFileUploadFailed function. It only occurs on some files not all. I have already confirmed it is not an issue with the file extension. I am also confident it is not an issue with file size.

Any ideas why this could be happening? What are situations where a 403 error would occur here? Are there any steps I could take to further narrow down the issue?

[Rumen]

Hi Kobi,

A 403 error generally indicates a permissions issue. Here are some potential situations and steps to troubleshoot:

• Exclude Telerik Handler from Authentication: Ensure the Telerik.Web.UI.WebResource.axd handler is excluded from authentication mechanisms like Windows Authentication and Forms Authentication. Configure your web.config as follows:
  

  <location path="Telerik.Web.UI.WebResource.axd">   
      <system.web>       
          <authorization>
              <allow users="*" />       
          </authorization>   
      </system.web>
  </location> 

• Network Configuration: The office network might have restrictions or firewall settings that block the POST requests to the Telerik.Web.UI.WebResource.axd handler. It's worth checking with the network administrator to see if there are any such restrictions in place.

• Web Server Security Settings: If the application is hosted on a web server within the office network, review the server's security settings to ensure that it doesn't block or restrict access based on specific criteria (like IP addresses, user agents, etc.) that might affect this particular user.

• Authentication and Authorization: Since the error is 403 Forbidden, it might be related to authentication or authorization issues. Ensure that the Telerik.Web.UI.WebResource.axd handler is correctly configured in the web.config file and is not inadvertently protected by authorization rules that might block some users.

• Proxy Servers or VPNs: If the office network routes traffic through a proxy server or VPN, it's possible that these could alter or block certain types of HTTP requests. Checking the configuration of these services might reveal if they're contributing to the issue.

• Follow our Red Dot Troubleshooting Guidance: Review the specific troubleshooting steps for the red dot issue at https://docs.telerik.com/devtools/aspnet-ajax/knowledge-base/asyncupload-red-dot-shown-file-not-uploaded-troubleshooting. 

 

If after checking these potential causes the issue persists, it might be helpful to gather more detailed logs from both the server and the client side during the failed upload attempt to further diagnose the problem.

 

Regards,
Rumen
Progress Telerik