Hello all,

We have a Staging site (behind Cloudflare with 2FA) which I've recently upgraded from Umbraco 7.15.5 to 7.15.7.

However, on the last screen of the upgrade I'm seeing "A server occurred this is most likely due to an error in Application Startup"

In chrome, the Console shows a 500 error for "/install/api/PostPerformInstall"

Opening the console error shows a "405 - HTTP verb used to access this page is not allowed"

I have followed the upgrade guide exactly, checked for breaking changes and version specific notes. I believe I have set everything up correctly

My web.config file has

<add key="umbracoUseSSL" value="true" />

With the rewrite rules as

    <rule name="HTTP to HTTPS redirect" stopProcessing="true">
      <match url="(.*)" />
      <conditions>
        <add input="{HTTPS}" pattern="off" ignoreCase="true" />
      </conditions>
      <action type="Redirect" url="https://{HTTP_HOST}/{R:1}" redirectType="Permanent" />
    </rule>
    <rule name="Exclude install folder from rewriting" stopProcessing="true">
      <match url="install/(.*)$" />
      <action type="None" />
    </rule>

Looking at the potential cause of the 405, I see that in the "umbraco.Installer.js" file a POST is made to the API.

function processInstallStep() {
  $http.post(Umbraco.Sys.ServerVariables.installApiBaseUrl + 'PostPerformInstall', _installerModel).success(function (data, status, headers, config) {

I think that the issue is occurring due to the redirect in the config above causing a change to the HTTP verb for the request during the install/upgrade.

Has anyone experienced this issue during Umbraco installations/upgrades? As far as I can see my config matches the official documentation but it looks like this will redirect HTTP to HTTPS - which in turn causes the 405 response.

If anyone has any thoughts or experience of this I would appreciate your input.

Thanks.