When you search the entirety of Stack Exchange from stackexchange.com, it displays the following error message:
Linked CSEs are no longer supported. See https://goo.gl/Gs1KIc.
This leads to instructions which say the following:
As announced earlier, Linked CSE and Auto CSE and will stop working on May 10th, 2017.
If your site is hosting a Linked CSE configuration or you make a request for search results by specifying a “cref” parameter, then you will need to use the CSE control panel to set your CSE configuration. It may be possible in some cases to upload your XML configuration file via the CSE Context tool found in the CSE control panel under the “Setup” → “Advanced”.
While making this transition, if your page has code that calls “google.search.CustomSearchControl” then you also will need to move to the current API.
Could this please be fixed?