i had same issue: first of all make sure you website iis setting is on 4.0(Integrated Pipleline) you can do under extensions section of your website setting on your hosting control panel. first:
and also make sure you remove WebDav module and handler in your web.config:
<modules>
<remove name="WebDAVModule" />
</modules>
<handlers>
<remove name="WebDAV" />
</handlers>