As the webUI now supports Service Layer for SAP 10+ versions, you may receive an error after setting up the connection.   This is an SAP Service Layer error, not related to the webUI. As the webUI consumes the ServiceLayer service, it displays the error returned from SAP ServiceLayer in order to help you to troubleshoot the issue.   The issue appears as follows, when the application tries to load some SAP settings:

Error. Http code: InternalServerErrorResponse: {"error": {"code": 299, "message: "Internal Server Error"}}

This is a known reported error, produced by a corrupted or wrong installation of the SAP Service Layer instance. You can check similar reported issues in the SAP network, like this one. The issue is raised because the SAP ServiceLayer is failing in serving the SQLQueries endpoint, that is required by the webUI application to retrieve some internal SAP database settings not exposed by others ServiceLayer endpoints. An easy test with Postman can confirm this. Just send a GET http request to the v2/SQLQueries endpoint of your ServiceLayer If ServiceLayer returns error HTTP 500 with the detailed SAP error 299 - Internal Server error, then you or your SAP partner should proceed to reinstall the service layer instance to get it working. When ServiceLayer is working, the result will be like the following, where the SQLQueries endpoint returns HTTP 200 as result.