Forge Server Tools · every failure mode · guides
Mod loading failed — the real cause is further down this report — FATAL
This is Forge's wrapper, not the error. Forge collects every mod that failed to load and then throws this summary. The actual failures are listed separately, below the stack trace.
Scroll PAST this stack trace to the 'Mod Loading Error' / 'The following problems were captured' section. Each entry there is a real error with a mod id attached -- those are what you fix. The trace above only tells you that loading stopped, which you already knew. If this tool found other FATAL items, they came from that section; fix those and this one disappears on its own.
Search your crash report or latest.log for any of these:
java.lang.Exception: Mod Loading has failed Description: ... Mod loading error has occurred dumpModLoadingCrashReport
The free edition covers the six most common startup failures, and this is not one of them — it is in the paid tool, which checks all 24 and names the mod jar from the stack trace. The fix above is the same one it prints, so you do not need it to solve this.