---
title: Updating a mod: important X4 9.00 changes
summary: Collisions, resources and events to recheck when adapting older examples.
section: data
kind: guide
status: reference
updated: 2026-10-27
tags: ["X4","modding","x4","version","migration"]
sources: ["https://wiki.egosoft.com/X4%20Foundations%20Wiki/Modding%20Support/Breaking%20Changes/"]
---
## Establish the version


This article targets 9.00. Official entries for future releases or individual betas do not establish behavior in your installed game.



## Recheck these areas


| Area | 9.00 change |
| --- | --- |
| Collisions | Reconvert old `.jcs`; new output is incompatible with older versions |
| Resources | Old region `<resources>` replaced by [resource areas](wiki:resource-areas) |
| `event_area_discovered` | Removed |
| `event_build_started`, `event_player_build_started` | `param2` is null; obtain the sequence through the `param3` buildtask |
| `GetEfficiencyUpgrades()` | Deprecated; returns an empty list |


The official table does not cover every shipped UI-script change. Compare the actual menu you hook.



## Plan your migration


1. List the data and calls your mod actually uses.
2. Identify relevant changes and preserve the old working sources separately.
3. Compare the relevant resources from both installations; fix the specific reference, signature or format.
4. Test one action in a new game, then upgrade an older save.
5. Use [version catalogs](wiki:version-catalogs) for differing files when supporting both games.



## Record the result


```text
Game: exact version + build
Changed part: one file or contract
Before: expected failure or old behavior
After: independently observed value/action
Save/load: pass, fail or not tested
```



This is a report template rather than evidence. Building successfully or passing XML validation does not establish collision, mining or event behavior. For models, start with the [official Blender toolkit](wiki:tool-blender).