The "Registration" Web Part appears to be causing a problem. The Web application at https://www.acer.europa.eu/Events could not be found. Verify that you have typed the URL correctly. If the URL should be serving existing content, the system administrator may need to add a new request URL mapping to the intended application.
Web Parts Maintenance Page: If you have permission, you can use this page to temporarily close Web Parts or remove personal settings. For more information, contact your site administrator.
Troubleshoot issues with Microsoft SharePoint Foundation.
Correlation ID: 647e7f92-1a9c-4c87-ad79-86e324e38b3e
Date and Time: 22/01/2018 08:02:08