• Forge Version: 14.23.5.2847
• BuildCraft Version (Add Hash if from github): 7.99.24.6-pre.2

crash report log : https://gist.github.com/Racpy/e8899119eb0558667e0970e045b31008

hmm looks like either your jar is corrupt, or one of the other mods is shipping an partial/outdated BC lib

This error only happened once , now work fine , nothing change mods
yes , there is a file named TileEngineBase_BC8$1.class in the buildcraft / lib / engine

Either that or something else is going wrong before then. Can you upload your full log file? That might contain more information about what's going on

crash full log : https://gist.github.com/Racpy/0572f4b8bf4d582a1975b0edfe8528d1

Thanks. Unfortunately that doesn't contain any more information, however I've had a look and it looks like the relevant class is an auto-generated one for a switch method over the buildcraft API class buildcraft.api.enums.EnumPowerStage. So maybe one of your mods ships an older version of that class? I'm not sure how to check to be honest...

One alternative would be to open the buildcraft-all-7.99.24.6-pre.2.jar file as a zip on your server and check to see if it contains a file called TileEngineBase_BC8$1 .class in the buildcraft/lib/engine folder.