The file did not change — the game did
Your .build file is frozen the moment it is saved. When a patch ships, the game's reader moves on but your file stays on the old format. That mismatch is what "broken after a patch" almost always means.
Patch troubleshooting
PoE2 Build Planner broken after a patch?
When a .build file used to load but suddenly fails after an update, the build itself is usually fine. The trick is to separate a folder/file problem from a format problem before you start deleting fields by hand.
Unofficial fan-made guide. Not affiliated with, endorsed by, or sponsored by Grinding Gear Games.
Why patches break a build file
The Path of Exile 2 Build Planner format is still experimental. Each patch can rename a field, retire a support gem, or change how slots are stored. A file exported before that change can suddenly stop matching what the game now expects — even though nothing about the file changed.
Valid JSON can still fail
A file can be perfectly valid JSON and still be ignored, because the game also checks that the values make sense for the current format. This is why "the file looks fine" and "the game loads it" are two different tests.
Isolate the failure in three steps
Run these in order. The goal is to find out where the break is before changing anything inside the build.
1. Validate the original file
Paste or select the .build file in the validator and check for invalid JSON, missing top-level fields, or obviously stale values. Everything runs locally in your browser — nothing is uploaded. If it fails JSON validation, fix that first; a corrupt file never loads regardless of the patch.
2. Test the folder with a minimal file
Download a minimal starter file and drop it in the same BuildPlanner folder as the broken build. If the starter appears in game, your folder and extension are correct, and the original build is the real problem. If even the starter does not appear, the issue is the folder or path, not the patch.
3. Re-export before hand-editing
If the source planner can export again, re-export after the patch and compare. Re-exporting is almost always safer than guessing which nested field a patch renamed and deleting it by hand.
Fields that commonly break after a patch
A valid JSON file can still fail when the game and the source planner disagree about the current Build Planner format. These are the usual suspects.
Support gems
Symptom: The build fails right after a patch that touched gems.
Check: Look for support gems that were renamed, removed, or no longer fit the linked skill.
Fix: Re-export from a current source planner instead of editing gem entries manually.
Charm or item slots
Symptom: The JSON validates but the build is ignored.
Check: Compare inventory, weapon-set, and charm slot values with a fresh minimal export.
Fix: Remove only the stale slot data you can identify confidently.
Ascendancy or class names
Symptom: The build loaded before but is now blank or rejected.
Check: A renamed ascendancy or class string can fall out of sync after a patch.
Fix: Re-export so the names match the current game data.
Path still wrong
Symptom: No build appears, including known-good files.
Check: Confirm the final folder is BuildPlanner, not one folder above it.
Fix: Use the platform path guide before touching the file at all.
When it is probably a folder issue
If both the original file and a minimal test file fail to appear, the patch is a red herring. Start with the BuildPlanner folder, the filename extension, and the Linux or Steam Deck Proton prefix.
When it is probably a format issue
If the minimal file appears but the original does not, the build data is stale. Validate the original, re-export after the patch, and avoid broad manual edits that can corrupt fields the game still relies on.
FAQ
My build worked yesterday and now it won't load. Did the patch delete it?
No. A patch does not delete your file. It changes what the game expects, so an older file can stop matching the new format. The file is still on disk — validate it, then re-export if the data is stale.
Should I edit the JSON to fix it?
Only as a last resort, and only for fields you can identify with confidence. Re-exporting from the source planner after the patch is safer because it regenerates every field to the current format at once.
How do I know if it's the folder or the format?
Drop a minimal starter file in the same folder. If it appears, the folder is fine and the format is your problem. If it doesn't, fix the folder/path first.
Will this validator guarantee my build loads?
No. It catches broken JSON and obvious missing fields, but it cannot predict every experimental format change. Treat it as a fast first check, not a guarantee.