Guidefor players3 min read

Create plus Xaero's Minimap train map crash, explained

Create's bridge to Xaero's Minimap draws train routes there. When Xaero renames an internal class it throws NoClassDefFoundError from Create's compat.

What the crash looks like

Create loads fine on its own. Xaero's Minimap and Xaero's World Map load fine on their own. Install all three together and, sooner or later, usually when a Xaero map screen opens while a Create train is nearby, the game throws:

java.lang.NoClassDefFoundError: xaero/map/gui/ScreenBase
  at com.simibubi.create.compat.trainmap.XaeroTrainMap.isMapOpen(XaeroTrainMap.java:130)

That trace, filed as issue #9817 against Create's own GitHub repository in January 2026, was reported on Create 6.0.8 with Xaero's Minimap 25.3.5 and Xaero's World Map 1.40.4, all on Minecraft 1.20.1. Players describe the same result in plainer terms: one asked whether Create was "compatible with Xaero's World and Mini Map again, because it used to break with 1.20.1," and another said they would like to use Create again but "for now I really can't since it breaks with the new Xaero's map mods."

Why this happens

Create does not just tolerate Xaero's Minimap and World Map sitting alongside it. It ships a dedicated compatibility class, com.simibubi.create.compat.trainmap.XaeroTrainMap, whose whole job is drawing Create's train routes directly onto Xaero's map screens. That is a real, deliberate feature: Create wants your train lines visible on the map you already have open, not hidden behind a separate menu.

Building that feature means Create's compat class has to reach into Xaero's internal screen classes, in this case xaero.map.gui.ScreenBase, to know when a Xaero map is open and where to draw. Xaero never promised that class would stay in that package, keep that name, or exist at all in the next release, because it is internal implementation detail, not a published API. When Xaero restructures its own code, Create's compat class can end up referencing a class that no longer exists in the shape it expected, and the JVM throws NoClassDefFoundError the moment Create tries to use it.

This is the same underlying shape as the OptiFabric and Fabric API crash covered elsewhere on this site: a first party writes a bridge into a second party's internals, the second party changes those internals for its own legitimate reasons, and the bridge breaks. Neither Create nor Xaero did anything wrong by the standards of their own project. The bridge is the fragile part, not either mod on its own.

Why players read this as "Create and Xaero don't work together"

The crash only surfaces when both mods are installed and a Xaero map screen opens near a train, so it looks exactly like a two mod conflict from the outside. But Create and Xaero's Minimap have no fundamental disagreement over rendering, world data, or mixins the way two competing performance mods might. The entire interaction between them is this one optional feature: routes drawn on the map. Remove that one class from the equation and the two mods have nothing left to fight over.

The fix

Update both Create and Xaero's Minimap and World Map to their current versions together, not just one side. The compat class only works when it matches what the installed Xaero version actually ships, so a new Create build paired with an old Xaero jar, or the reverse, can still trip the same crash even after one side has moved on.

If you update both to their latest compatible releases and the crash still happens, report it against Create's own issue tracker, referencing issue #9817 if it looks like the same trace. The crashing code is Create's, so only Create's maintainers can re-point it at whatever Xaero's current internal class structure looks like. Filing it against Xaero's tracker instead will not get the compat class fixed, since Xaero didn't write it and has no reason to change internals back to match a class they never agreed to keep stable.

If you need train routes on the map right now and updating doesn't resolve it, removing Xaero's Minimap or World Map stops the crash immediately, since Create's compat class has nothing left to hook into. That costs you route rendering on the map, not any other part of either mod. Both mods otherwise keep working fully on their own.

Frequently asked

Are Create and Xaero's Minimap actually incompatible?

No. There is nothing structurally incompatible between a logistics and automation mod and a map mod. What breaks is a small, specific piece of code Create ships on purpose to draw its train routes on top of Xaero's map screens. When that code's assumptions about Xaero's internals go stale, it crashes, and the crash looks like a mod conflict even though the two mods coexist fine everywhere else.

What's the actual error?

java.lang.NoClassDefFoundError: xaero/map/gui/ScreenBase, thrown from com.simibubi.create.compat.trainmap.XaeroTrainMap.isMapOpen. That is Create's own class, in Create's own compat package, failing to find a class it expected inside Xaero's jar. It is not an error coming from Xaero's code.

Whose fault is this, Create's or Xaero's?

Neither, in the sense of either project doing something wrong by its own standards. Xaero's Minimap and World Map do not publish their internal screen classes as a stable API, so Xaero is free to rename or restructure them between releases. Create chose to hook directly into those internals to render train routes on the map, which is genuinely useful when it works, but it means Create's compat class owns the job of keeping up, and it does not always keep up right away.

Do I need to report this to Create or to Xaero?

Create. The crashing class lives in Create's own compat.trainmap package, and only Create's maintainers can update it to match Xaero's current internals. Xaero's issue tracker cannot fix a class they don't own and likely didn't change on purpose to break anything.

Will removing Xaero's Minimap fix it?

It will stop the crash, since the compat code has nothing to hook into anymore, but it also means you lose train route rendering on the map entirely. Updating both mods together is usually the better fix; see below.

Does this only happen with Xaero's mods, or with other minimap mods too?

This specific crash is unique to Xaero's Minimap and World Map, because those are the two map mods Create ships first-party compat code for. Other minimap mods that Create has no bridge to simply won't show train routes at all, which is a missing feature, not a crash.

Last reviewed 2026-08-05. Version data on this site updates automatically; this guide is reviewed by hand when the ecosystem changes.