I do think that the region of the city You are attacking must have forests/woods in them to build the siege engines from, like trebuchets etc. At least I have some memory of that being the case, or stated in earlier OpenDevs somewhere. Possibly even within the battlefield area. I see alot of desert there around the city, so maybe that is the issue ???

Acctually @2DKiri had this exact same issue in her current stream. She tried reloading, as well as restart the siege many times, but still could not build any siege units. Yes, it could be that You are behind in techs too. Bug or intended I'm not sure ??? She was in Industrial era, but behind in techs and could not build any siege engines from earlier eras that she had reserched earlier.

Either that or possibly the forest/wood thing I suggested earlier. I would lean towards the issue with being behind in techs, intentional design or bug. Not 100% sure, since I have never been in this situation myself.

It kind of make sense. Sure You could bring some catapults, ballistas or trebuchets to a modern siege battle irl, but I doubt they would do much and also be easily destroyed, so it would be more or less pointless. Maybe that is the intention if it is an intentional design.

Ok @Konrow I have now asked some of the other VIP behind the scene tester that knew about this. Since I have never been that far behind in techs myself compared to the AI and had a siege. I try to make tech catch up to th era I am in myself.

The VIP tester @Narcisse was kind to reply really fast after I asked, that once You have researched "Mortars", You can no longer build outdated siege engines. You must then instead build acctual units and bring with You in Your armies, Units which have kind of siege/range abilities like mortars, cannons, artillery etc. 

So that answers that. Not a bug, but an intentional design then.

I also had this problem, except in my case, I was laying siege to a place when I changed eras. It went from building a trebuchet to not building anything. Where I wanted two trebuchet, I ended up with only one because I could not build another. I also had not reached mortars.

Additionally, in contrast to what Lord_Funk says about it making sense, no it didn't. I was the one who changed eras, not them. Their walls were still wooden. A trebuchet would have laid waste to their defenses, and the one I did have did exactly that. Having a second one would have made the battle even shorter, with far less damage to my side. I would only agree with the sentiment that it makes sense if *they* are the ones going up an era *and* they improve the defenses of the city to some level that makes my siege engine irrelevant *before* I finish the siege engine.

So, yes, it's a bug, since it happened on era change, not technology change.

As Lord_Funk explained, it's currently an issue with the design of Early Modern Era. I don't know if it happens in this closed beta because you entered Early Modern Era OR because you unlocked the Early Modern Mortar. But it's totally unrelated to you opponent advancement.

But in term of design we are supposed to produce Siege Units (the mortar for exemple) in this era than we are taking in our army, instead of building siege engines on site, as previous era. (to change a bit the vibes of battles through era).

Obviously I agree than that "delay" of not being able to build trebuchet when we didn't build any mortars yet is really annoying. It really create odd situation, like suffering from this change when we are already in some wars.

So it's nice to feedback it, I hope this issue will be adressed as sooner as possible ;)

There is several possibilities to fix this issue so I am rather confident.

Throwing suggestions : making trebuchets weak and almost ineffective on Early Modern walls, so players will always be able to build trebs, but it will induce players to replace their use by Mortars. And maybe only removing trebs when we build at least one Heavy Weapon (class of unit of the mortar) and when we reach a later tech. Or introducing this change of doctrine with some event which give a mortar.

I obviously always wish to have an average (but not as good than mortar) early modern siege engine build on site, to have a smoother transition from the treb, a late medieval siege bombard. :p

So this is what happened! I researched Trebuchets at about the same time as I progressed to the Early Modern Era and figured that trebuchets were just broken. Guess I'll have to amend the bug report I made. I don't even think I ended up researching Mortars that game... Maybe the outdatedness of Trebuchets should only come around if you have a Mortar in the siege?

Narcisse wrote:

As Lord_Funk explained, it's currently an issue with the design of Early Modern Era. I don't know if it happens in this closed beta because you entered Early Modern Era OR because you unlocked the Early Modern Mortar. But it's totally unrelated to you opponent advancement.

I hadn't unlocked early modern mortar, only switched ages. In effect, I had no siege weapons at all until I got to mortars. I had to rely on infantry assaulting the walls. Also, my enemies never had anything but wooden walls since they were way behind me (I never fought with the AIs that were with me in tech). Those trebuchet would have been highly effective even after I researched mortars.

EDIT:

Meant to mention that I agree with your suggestions Narcisse. It would have made the most sense to keep making trebuchet until mortars come online. If you have never had a mortar (even if you know how to make one!), why would you stop teaching your armies how to make trebuchet?

MorshuHimself wrote:

So this is what happened! I researched Trebuchets at about the same time as I progressed to the Early Modern Era and figured that trebuchets were just broken. Guess I'll have to amend the bug report I made. I don't even think I ended up researching Mortars that game... Maybe the outdatedness of Trebuchets should only come around if you have a Mortar in the siege?

Yeap. So would be nice to report it.

Aloriel wrote:
I hadn't unlocked early modern mortar, only switched ages. In effect, I had no siege weapons at all until I got to mortars. I had to rely on infantry assaulting the walls. Also, my enemies never had anything but wooden walls since they were way behind me (I never fought with the AIs that were with me in tech). Those trebuchet would have been highly effective even after I researched mortars.

Indeed. It's why I was saying, than even with the unlock of mortar, it shouldn't be removed in any case like that. Eventually way later. Because it is generating an huge delay. There is a bunch of time before we will build a decent amount of mortars, and before other players will research Early Modern walls.

It miss some step to experience this change of military doctrine smoothly

Long time I didn't watch it, I will take a look for sure.

Ok, so it seems it was kind of what I expected. Not necessarily a "bug" per se but not great in terms of design either. Thank you for all the answers and feedback, everyone. Like Aloriel, mentioned, I too had not researched mortars yet, simply advanced eras. If they continue to not be linked and if the large disparity between tech and era that many people encountered stays, I hope they change this because it just feels strange. Siege can play a pretty big role in city fights. Also my enemy had stone walls, if I could bring my trebs in, I could take em down, don't force me to use mortars that I don't know how to make yet lol. Also why take away siege machines building during siege in later eras completely? It would seem like the game should have more options and be sped up by then instead of taking away options. Why take away the benefit vs cost assessment of maintaining a siege just because your in early modern era now?

Lord_Funk wrote:

...It kind of make sense...

Aloriel wrote:

...Additionally, in contrast to what Lord_Funk says about it making sense, no it didn't... Do not confuse me saying that it "kind of make sense" with that I think it's a good mechanic, or design choice. I have never had it happen to me personally, but reading how it has affected others, as well as watching it happen in the 2DKiri stream earlier, I do agree that it causes some very weird scenarios where You can end up doing a siege and not have the more modern units, like mortars, but at the same time not being able to build any other siege weapons either. Very annoying.

Aloriel wrote:

...Additionally, in contrast to what Lord_Funk says about it making sense, no it didn't...

@Aloriel Do not confuse me saying that it "kind of make sense" with that I think it's a good mechanic. I have never had it happen to me personally, but reading how it has affected others, as well as watching it happen in the 2DKiri stream earlier, I do agree that it causes some very weird scenarios where You can end up doing a siege and not have the more modern units, like mortars, but at the same time not being able to build any other siege weapons either. Very annoying.

If it is a bug triggered by era, or if intentional by inventing Mortar units, doesn't matter as far as my opinion on it. It is still annoying and should be looked at by the devs imo.

I agree with You, @Narcisse, @Konrow and @MorshuHimself that it definetly needs some type of solution to not be like that.

If it is a bug (or even an intentional design) triggered by era, or if intentional by having researched Mortar units, doesn't matter as far as my opinion on it. It is still annoying and should be looked at by the devs for some better way to handle that imo.