Trying to get an ols modified modpack running again

[SupSup30]

Hello,

I'm currently trying to get a modpack in the Technic Launcher (tekkit-legends) working again. I modified it and added some new Mods in 2022 and it worked wonderfully back then. At some point in the meantime I bought a new computer and swapped the hard drives. Now I've copied the folder of the old Technic installation to the new hard drive, but when I start the modpack I immediately get the following error log:

[B#831] OS: windows 11
[B#831] Identified as windows
[B#831] Java: 1.8.0_391 64-bit (amd64)
[B#831] minecraft.net resolves to [13.107.246.67]
[B#831] session.minecraft.net resolves to [13.107.246.67]
[B#831] textures.minecraft.net resolves to [13.107.246.67]
[B#831] libraries.minecraft.net resolves to [13.107.246.67]
[B#831] account.mojang.com resolves to [88.221.110.169, 88.221.110.249]
[B#831] www.technicpack.net resolves to [104.26.6.125, 104.26.7.125, 172.67.70.48]
[B#831] launcher.technicpack.net resolves to [174.127.114.237]
[B#831] api.technicpack.net resolves to [104.26.6.125, 104.26.7.125, 172.67.70.48]
[B#831] mirror.technicpack.net resolves to [174.127.114.237]
[B#831] solder.technicpack.net resolves to [104.26.7.125, 172.67.70.48, 104.26.6.125]
[B#831] files.minecraftforge.net resolves to [172.67.161.211, 104.21.58.163]
[B#831] user.auth.xboxlive.com resolves to [137.116.225.129]
[B#831] xsts.auth.xboxlive.com resolves to [52.156.147.113]
[B#831] api.minecraftservices.com resolves to [13.107.246.67]
[B#831] launchermeta.mojang.com resolves to [13.107.246.67]
[B#831] piston-meta.mojang.com resolves to [13.107.246.67]
[B#831] Don't need to inject new root certificates: Java 8 is 101+ (1.8.0_391)
[B#831] User deserialization
[B#831] Deserializing microsoft user
[B#831] Starting download of https://minotar.net/helm/9b7e060086d54a969c4b23704670a69a/100, with 3 tries remaining
[B#831] Starting download of https://www.gravatar.com/avatar/777da0eed8908835b1e9e08204f5beb2?s=60&d=retro, with 3 tries remaining
[B#831] Starting download of https://www.gravatar.com/avatar/417979e451a4ed37c22f5340a9c3cd4a?s=60&d=retro, with 3 tries remaining
[B#831] Starting download of https://cdn.technicpack.net/platform2/pack-logos/735902.png?1631990177, with 3 tries remaining
[B#831] Starting download of https://cdn.technicpack.net/platform2/pack-backgrounds/735902.jpg?1631990177, with 3 tries remaining
[B#831] Starting download of https://cdn.technicpack.net/platform2/pack-icons/735902.png?1631990177, with 3 tries remaining
[B#831] Starting download of https://cdn.technicpack.net/platform2/pack-icons/735902.png?1631990177, with 3 tries remaining
[B#831] java.lang.RuntimeException: No asset index detected, cannot continue
[B#831]     at net.technicpack.minecraftcore.install.tasks.EnsureAssetsIndexTask.runTask(EnsureAssetsIndexTask.java:75)
[B#831]     at net.technicpack.launchercore.install.tasks.TaskGroup.runTask(TaskGroup.java:85)
[B#831]     at net.technicpack.launchercore.install.InstallTasksQueue.runAllTasks(InstallTasksQueue.java:49)
[B#831]     at net.technicpack.launchercore.install.ModpackInstaller.installPack(ModpackInstaller.java:42)
[B#831]     at net.technicpack.launcher.launch.Installer$1.run(Installer.java:124)
[B#831]     at java.lang.Thread.run(Unknown Source)
[B#831] Starting download of https://cdn.technicpack.net/platform2/pack-icons/735902.png?1631990177, with 3 tries remaining

I have also tried updating the modpack using the Technic Launcher. Then the modpack starts without any problems, but only in the original version. Simply replacing the modpack then leads to this error message again.

Is there anything I can do or is the modpack just broken?