A common cause of this error is the WebDAV Publishing feature being installed as a part of Internet Information Services. This feature may block certain HTTP verbs needed for ClearSCADA Mobile to function correctly. Please follow the steps below for resolution:
1. Launch Internet Information Services (IIS) Manager and locate the _ClearScadaMobile_ website.
2. Click on the _ClearScadaMobile_ website and open Handler Mappings by locating this feature in the IIS section, right clicking on it and selecting Open Feature.
3. In Handler Mappings, locate the WebDAV handler and double click on it to view its properties.
4. In the Edit Module Mappings window, click on Request Restrictions.
5. Once the Request Restrictions window is shown, click on the Verbs tab, select All Verbs and click OK to apply the change.
6. Select the ClearScadaMobile website again and restart the website by clicking on _Restart_ in the Manage Website section.
7. Restart the mobile application in the mobile device and try to connect again.
The mobile website is named ClearSCADA in ClearSCADA 2015 R1. It is named ClearScadaMobile in other versions of ClearSCADA.