I have my VE cleanly installed and running fine until we started using templates. Any article with template, once saved, cannot be edited again with VE, and yields Error contacting the Parsoid/RESTBase server (HTTP 500) instead. But once the template tags are removed in the source code, the article become editable in VE again.
Topic on Extension talk:VisualEditor
Hello, you should provide some information about the MediaWiki version and the environment - the PHP version, OS, so on.