Doorway Closed

Sometimes a simple answer is the best answer. After blasting several mountains into gravel and dumping the result into the portal, it seems to have been overloaded. Or, perhaps, was deliberately shut down. Regardless, the remaining material was dumped on top of the site in case it ever re-opens. The experience of such a large engineering and mining project will also prove useful in other areas.

The command below will trigger the "Doorway Closed" event in Stellaris:

When this event fires, you can choose between the following option:

• Excellent.
  • The Portal site can still be studied, but it will provide less useful data.
  • Engineering: +None to None