HTTP 405 Error in .NET Web App

I was recently told that an web app I had developed was returning an HTTP 405 error upon being freshly deployed. It took me way too long to realise that cause of the issue came down to missing files. Specifically, the complete folder structure had been deployed however the files at the top level web root were missing. These are files are rather critical.

They are the web.config and global.asax

If you are seeing this error, ensure these files have been deployed correctly and aren’t corrupt as a first point of call.

Receiving an HTTP 405 in IE11
Receiving a 405 in IE11

For SEO HTTP 405

  • Chrome: The page you are looking for cannot be displayed because an invalid method (HTTP verb) is being used.
  • IE: HTTP 405 The website has a programming error. This error (HTTP 405 Method Not Allowed) means that Internet Explorer was able to connect to the website, but the site had a programming error.
  • Edge: HTTP 405 error That’s odd… Microsoft Edge can’t find this page

Paul.

Deployment failure causing Get-SPSite to fail

I run a scripted deployment process each time new (SharePoint) solutions are ready for QA, or any environment for that matter. We script a series of commands, specifically:
Uninstall-SPSolution, Remove-SPSolution, Add-SPSolution and finally Install-SPSolution.

Before running these commands, along with a number of other checks, we perform Get-SPSite to ensure the site is available and fail early if need be. If our custom solution has not been deployed then viewing any page under any of the web application’s site collections fails with an exception due to a failure to find one of the solution assemblies. This is because we have custom membership and claims providers which are defined in the solution assembly and are referenced in the web.config for the web application. Despite this, any SPSite and SPWeb objects can be obtained safely via PowerShell as forms authentication is not taking place.

So I was surprised to find that the Get-SPSite check failing during deployment today with a failure to locate the assembly containing the membership and claims providers. I did not discover the root cause as to why this suddenly occurred but will outline what it took to fix it.

In the end I was able to ” Install-SPSolution -force ” to recover from this situation but not before stopping and starting the SharePoint Administration Service across all Web servers in the farm. The service was not stopped on any of the machines however the Install job was never completing despite the timer job history in Central Administration stating that the job had been successful. Upon restarting all this service the Install-SPSolution command would then complete.

Credit to Andreas’ blog for putting me in the right direction.

The _layouts web.config for customErrors

There is a web.config file under the _layouts folder. This is worth being aware of as you may notice that files that you access from the _layouts folder may not behave as you would expect. This came to my attention when I was getting the following error:

”To enable the details of this specific error message to be viewable on remote machines, please create a tag within a “web.config” configuration file located in the root directory of the current web application. This tag should then have its “mode” attribute set to “Off”.

This initially surprised me as I knew that I had already done as such and had recently seen the default error screens when I was building web parts on content pages.

As the web.config under the layouts folder is deeper in the site hierarchy, any elements defined here will overwrite those defined at the web application level. By default the customErrors element exists at this level and it must be set accordingly to your needs as well.

As always, be careful when editing web.config files and always make a backup beforehand.