Symptoms
When trying to delete a record from a MySQL table using Webadmin at Customer Control Panel > Websites > Databases some browsers may show the error Server not found. Some browsers may just do not refresh the page. If reload the page it is seen that the record has been deleted.
Cause
Such behaviour has been considered as a software issue #PPA-2596 .
Resolution
The issue has been fixed in MU 19. Please install all the updates to fix the issue.