Hi Magnus,

Do you have a web.config rewrite rule that is removing trailing slashes from URLs? I've encountered this same issue, and that was the cause.

From what I've been able to work out, Umbraco 7+ expects the URL of the preview page to be something like:

http://localhost:1234/umbraco/preview/?id=1234#?id=1234

Adding a standard rewrite rule to remove trailing slashes results in a URL like the one in your screenshot, with no slash between 'preview' and the query string. This causes several requests for scripts and stylesheets that the preview mode relies upon to return 404 errors.

I managed to work around this by adding a condition to my rewrite rule that ignores Umbraco Back Office URLs.

<rule name="Remove trailing slash" stopProcessing="true">
    <match url="(.*)/$" />
    <conditions>
        <add input="{REQUEST_URI}" pattern="^/umbraco.*$" negate="true" />
        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
    </conditions>
    <action type="Redirect" redirectType="Permanent" url="{R:1}" />
</rule>

Hi Stephen,

Thank you for reaching out!

I have the following rewrite rules in my web.config file:

<rewrite>
        <rules>
            <rule name="Redirect HTTP to HTTPS" stopProcessing="true">
      <match url="(.*)" />
      <conditions>
        <add input="{HTTPS}" pattern="off" />
      </conditions>
      <action type="Redirect" url="https://{HTTP_HOST}/{R:1}" redirectType="Permanent" />
            </rule>
            <rule name="Redirect to non-www" stopProcessing="true">
                <match url="(.*)" />
                <conditions>
                    <add input="{HTTP_HOST}" pattern="www\.filuren\.dk$" />
                </conditions>
                <action type="Redirect" url="http://filuren.dk/{R:1}" redirectType="Permanent" />
            </rule>
             <rule name="Remove trailing slash" stopProcessing="true">
                 <match url="(.*)/$" />
                     <conditions>
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                     </conditions>
                  <action type="Redirect" redirectType="Permanent" url="{R:1}" />
             </rule>
             <rule name="Remove trailing slash2" stopProcessing="true">
                 <match url="(.*)/\$" />
                     <conditions>
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                     </conditions>
                  <action type="Redirect" redirectType="Permanent" url="{R:1}" />
             </rule>
             <rule name="Remove trailing slash3" stopProcessing="true">
                 <match url="(.*)//$" />
                     <conditions>
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                     </conditions>
                  <action type="Redirect" redirectType="Permanent" url="{R:1}" />
             </rule>              
        </rules>
    </rewrite>

Should i rewrite the rewrite rules? ;)

I don't seem to have the REQUEST_URI input.. But i am not that familiar with rewrite rules.

Thank you in advance.

hey Stephen

Sorry for the slow reply!

That worked - Thank you so much.

Have a great day!

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