Is the other rift active and you already were in the system? (I assume that is the case if it is in your empire)
In theory it should be working like the l gates just with the extra step of needing to be explored like a wormhole first.
Have you checked if you are able to explore the other rift from the side of the rift, not the nexus?

Yes, I have science ships next to the rifts in all 3 systems but no option to explore the 3rd rift...

I guess you are using a lot of mods and I wouldn't be able to load the savegame with only mem?

I'm running 19 mods in my current game (most of them Real Space and Guilli)

Ok no problem. I just created a testevent for this situation.

So my setup was: New game, with gates active, spawned a starbase in each system with an active rift, spawned a scienceship in each of those systems, researched all technologies to be able to use the rifts.

Now I used the scienceship in one of the systems (with scientist) to explore the first rift. Worked. Could send it through to the nexus. But wasn't able to send the ship to any of the other systems as the rifts were not yet explored.

Then I used the next scienceship in another system with an unexplored rift put a scientist in and explored that rift. Now I was able to pass through that one as well. Works exaclty as intended on my end.

Did you do anything differently?

No, I came across the first rift very early in the game and I conquered the system with the 2nd rift later. After that I researched the tech and I opened the first one, claimed the nexus and I wasn't able to explore the other one. I remember it happening in another game too and I thought I needed to repair the Habitat in the nexus first but that didn't help...

Having the Nexus does not accomplish anything in itself as I explained. You have to explore from the side of the Rift endpoints to be able to navigate them.

Can you check again just to make sure that you indeed are unable to do so? If this was the case then I'd have a problem to replicate the issue.

https://steamcommunity.com/sharedfiles/filedetails/?id=2793937090
This one is open

https://steamcommunity.com/sharedfiles/filedetails/?id=2793937035
This one I can't open

Update: Apparently you need 2 techs for some rifts (Rift travel AND rift stabilization). I had no idea so I apologize for the inconvenience! I still love the mod though, it's a must have!

Originally posted by Kuroda:

Update: Apparently you need 2 techs for some rifts (Rift travel AND rift stabilization). I had no idea so I apologize for the inconvenience! I still love the mod though, it's a must have!

Ah I see. The RUINED ones are broken and need to be restored first like inactive gateways. This is why I asked if all your rifts were active. So in this case everything is working as intended.
No inconvenience at all. If anything were broken, a detailed description of the problem is very helpful. (even better though if nothing is broken :) )

Reviving this thread since it is the only result when searching. I'm having this issue, but I am well into the repeatable endgame research (tier 6 on most repeatable techs). The stabilization tech has yet to appear.

I don't have any broken gates in my empire and I am well ahead of my neighbors in research, so they don't have that tech either. So Gateway Activation tech is not appearing (this is the reason I was hoping to use rifts instead since a rift is at each end of my borders),

Is the stabilization tech a re-skin of the Gateway Activation tech? I realize this is an edge case, but since it acts as a substitute for gate tech, it probably shouldn't be reliant on having found a broken gate it in the same way, assuming that it is currently. If it's not that, I have no idea why the tech isn't appearing

Had several playthroughs recently, but never got the Rift Stabilization (counting only playthroughs with Rifts exiting, every time got to repeatables, restored Star Throne).