How to Fix an All The Forge Server That Keeps Crashing
All The Forge is a broad NeoForge kitchen-sink for Minecraft 1.21.1, covering a wide range of tech and magic mods alongside exploration content and a light quest framework — it fills the same niche for the NeoForge 1.21 ecosystem that All the Mods fills elsewhere. That breadth is exactly what makes crash troubleshooting on this pack a little different: the fixes below focus on the Java version mismatch and mod-interaction issues that are the most reported causes on wide-coverage packs like this one.
See the All The Forge pack page for the full RAM and setup breakdown before you chase anything else.
1. Wrong Java version from a previous pack
NeoForge on Minecraft 1.21.x requires Java 21 to boot at all. If this server (or this host account) previously ran an older modpack, it's common for the Java runtime setting to still be pointed at Java 8 or Java 17 from that earlier install. This shows up as an immediate boot failure rather than a crash mid-session, usually with the server process exiting within the first few seconds of startup.
- Confirm the server is explicitly set to Java 21, not 'auto' or a leftover value
- A boot failure in the first few seconds (before the world even starts loading) points here first
2. Mod-interaction conflict in a broad modlist
A kitchen-sink pack like All The Forge bundles a wide spread of tech, magic, and exploration mods to cover a lot of ground at once. That breadth is the appeal, but it also means the odds of two specific mods stepping on each other go up compared to a smaller, narrowly-scoped pack — the same pattern seen on other wide-coverage kitchen-sinks for the same reason.
If a crash started after adding a mod, updating one, or changing a config, treat that change as the first suspect rather than assuming it's a core engine problem.
3. Crash tied to a specific world area or structure
On broad modpacks, crashes that only happen when a specific player enters a specific chunk or structure are usually tied to a particular mod's world generation or entity logic rather than the server as a whole. If the crash log points at a specific mod and the crash is reproducible in one location, that mod (or its interaction with a neighboring one) is a stronger lead than a general stability issue.
4. Corrupted config or a stale world after a mod update
Updating individual mods inside a kitchen-sink pack (rather than updating the whole pack as a unit) can leave a config file in a format the updated mod no longer expects, or leave saved world data referencing a block or item ID that changed. This tends to produce a crash that's consistent and repeatable on every boot, rather than one that only happens under load — which is a useful way to tell it apart from a RAM or performance issue.
5. RAM under the pack's realistic floor
8 GB is the real floor for All The Forge, and it's worth treating as a hard minimum rather than a starting point to shave down. Running below that floor rarely causes an instant, clean crash — what actually happens is rising lag and longer garbage-collection pauses as the server tries to keep up, which then escalates into a tick timeout or watchdog crash once enough players, chunks, or entities are loaded at once.
FAQ
Why does my All The Forge server fail to boot right after an update?+
The most common cause is a leftover Java install from a previous pack. NeoForge on Minecraft 1.21.1 requires Java 21 specifically — if your server was previously running an older modpack on Java 8 or 17, the launcher may still be pointed at that old runtime. Check your server's Java version setting and make sure it's explicitly Java 21 before assuming the crash is mod-related.
Is it normal for a kitchen-sink pack like this to have more crashes than a smaller pack?+
Yes, relatively. A broad kitchen-sink pack bundles a very wide range of tech, magic, and exploration mods, which raises the odds of two specific mods interacting badly compared to a narrower, curated pack. This is a known pattern across wide-coverage kitchen-sinks, not something unique to this pack — it just means troubleshooting should start with 'what did I add or change recently' rather than assuming a core engine bug.
How much RAM does All The Forge actually need to run without crashing?+
8 GB is the real floor for stable play, not a generic guess. Running below that doesn't usually produce an instant clean crash — it shows up first as rising lag and longer garbage-collection pauses under load, which then escalates into a tick timeout or watchdog crash once enough players or chunks are loaded.
Host All The Forge on hardware sized for its real floor
All The Forge needs a real 8 GB floor to stay stable under load, and taking a backup before any mod update or config change keeps a bad change from turning into a lost world.
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