Attempted to select a specific version for the modpack that I am using (ATM9). Selected the version in the config of AMP, clicked “updated” and then attempted to start the server. Still saying that it is missing the latest forge version, even though it is not the one currently selected.
Reproduction Steps
Create a new Minecraft Instance.
Change the configuration file to “Forge”.
Change the version to “Specific version”.
Select Forge version 47.3.7 (1.20.1)
Attempt to start the server.
Notice that the manager is saying that ./Minecraft/forge-1.21-51.0.33-shim.jar is missing even though it is not the version selected.
You need to press the download/update button (after selecting the version)
If that doesn’t work, stop/start the instance from the main panel.
And the server’s Jar must be Autoselect
Yup, did that. The server jar is also on auto select. Also tried deleting the .jar manually and updating again, same problem.
Also tried stopping / starting the instance again. (Twice, before and after you answered)
It keep saying:
Unable to start server.
The update manager reported a successful update, but ./Minecraft/forge-1.21-51.0.33-shim.jar is missing.
If I delete the installer and click “update”, it does download the correct installer that was selected. forge-1.20.1-47.3.7-installer.jar, but the problem still persists.
Try swapping the version to 1.21.1 temporarily, hit download/update, then switch back to 1.20.1 and hit download/update again.
Forge changed how it handles Jars a couple updates ago and AMP had to kinda make things work internally, so every now and then there’s some weird mismatch bug
Solution: Do not delete the AMP files that are present. Just paste your modpack files on top of it. (And as always, make a backup just in case)
I actually seem to have gotten it to work.
I had deleted every file in the Minecraft folder of AMP to replace it with the modpack’s server file. But I did do a backup of those AMP file just in case. So I put them back in alongside the new modpack’s server file (especially the forge-1.21-51.0.33-shim.jar file) and started the server. As expected, it did not give the error since the file was present but surprisingly, the server managed to start either way? Is it correctly using the correct version of Forge, which should be forge-1.20.1-47.3.7 or is it mistakenly using the 1.21 51.0.33 version?
(Note: At this point I am able to connect and play on the server I’m just not understanding what’s going on here)
Yeah, from what I can gather the jar-detection got stuck looking for 1.21 (which might’ve been at the top of the list when you swapped to Forge), then didn’t change over whatever detection-stuff when you swapped it to 1.20.1. Then when you went to start things, AMP went: “holup, I can’t find the Jar, this is crazy because I know we updated, but where is it?!?!”
I do quite a bit of version switching to test mods and I’ve never been able to reliably get this to happen (I can get a similar issue to happen, but never this exact one)
So when the Jar was there, AMP went: “yep, this totally checks out” and started 1.20.1 fine it’s AMP’s emotional support Jar
