Path of Exile 2 0.5.0 Build System Crash Corrupted Build Files Fix

What is the Path of Exile 2 0.5.0 Build System Crash?

Patch 0.5.0 (released May 27, 2026) introduced Path of Exile 2's redesigned in-client build planner — players can save passive trees, gem links, and gear loadouts directly inside the client instead of using external tools like PoB. Unfortunately the new save format triggers a hard crash for a large subset of players. The crash dialog reads "Path of Exile 2 has encountered a problem — Deadlock detected while serializing build data" and dumps a stack trace pointing at BuildSerializer::SaveLoadout() inside Engine.dll.

Grinding Gear Games acknowledged the issue May 29, 2026 and shipped a May 30 hotfix (build 0.5.0c) that addresses the deadlock in most cases, but a corrupted build file written before the hotfix will keep crashing the client even after the patch lands. The fix requires both updating to 0.5.0c or later AND manually deleting the corrupted Builds.bin so the client regenerates a clean copy. Some players also report startup crashes on MSVCP140.dll during the migration step that runs the first time you launch 0.5.0.

When does it occur?

• The client crashes during the splash screen the first time you launch after the 0.5.0 update
• Opening the new "Builds" panel from the character screen freezes the client for 30+ seconds then crashes
• Saving a new build with more than 12 socketed support gems triggers the deadlock instantly
• Switching characters in town after editing a build pops "Deadlock detected" and the client closes
• An old build imported from PoB community export string crashes on import
• The client crashes silently with no error dialog on startup — only Logs\Client.txt shows BuildSerializer FATAL

Common causes

• A **corrupted Builds.bin** was written before the May 30 hotfix and persists in %AppData%\Path of Exile 2\
• The client is still on 0.5.0a or 0.5.0b — only 0.5.0c (May 30 hotfix) or later includes the deadlock fix
• The Steam content depot did not fully update because of a peering issue — partial install of the new Engine.dll
• Antivirus quarantined BuildSerializer.dll mid-write, leaving a truncated file
• A PoB build import string longer than 32 KB overflows the new in-client parser
• The cloud-save sync from GGG's account servers pulled a build saved by another character on the same account
• OneDrive or another sync client is locking Builds.bin while the client tries to rewrite it

Step-by-step fixes

1. Update to 0.5.0c or later first. In Steam, right-click Path of Exile 2 → Properties → Updates and confirm the client shows version 0.5.0c or higher (the title screen prints the version in the bottom-right). If Steam reports the game is up to date but the title screen still shows 0.5.0a/b, fully exit Steam, restart it, and let it re-check. For the standalone client, the patcher auto-pulls — close and relaunch.

1. Delete the corrupted build file so the client regenerates a clean one. With the client closed:

   ren "%AppData%\Path of Exile 2\Builds.bin" Builds.bin.old
   ren "%AppData%\Path of Exile 2\Builds.idx" Builds.idx.old

Both files live in C:\Users\<you>\AppData\Roaming\Path of Exile 2\ for the standalone client, or %LocalAppData%\Path of Exile 2\ for the Steam version. Re-launch the client — it will create empty replacements on first build save.

1. Disable cloud build sync temporarily to avoid pulling the corrupted version from GGG servers. Log in via the launcher, click Settings → Account and toggle "Sync builds across devices" to Off. After your local build saves work for 24 hours, you can turn it back on.

1. Verify game integrity. In Steam: right-click Path of Exile 2 → Properties → Installed Files → Verify integrity of game files. For the standalone client, run Pathofexile2_x64.exe /check from the install directory. Expect a 1–3 GB re-download if Engine.dll, Content.ggpk, or the new BuildSerializer.dll is partial.

1. Add an antivirus exception for the install folder. Open Windows Security → Virus & threat protection → Manage settings → Exclusions → Add an exclusion → Folder, then add C:\Program Files (x86)\Grinding Gear Games\Path of Exile 2\ (or your Steam install path). Third-party AV (Bitdefender, Kaspersky, Avast) is the most common culprit for the truncated BuildSerializer.dll.

1. Re-import PoB builds in smaller chunks if a single import string crashes. Split the build into a passive-tree-only import and a gear-only import using the PoB community fork's "Export → Skill tree only" option. The new parser handles two 16 KB imports cleanly but deadlocks on a single 32+ KB string.

1. **Disable OneDrive sync for the %AppData%\Path of Exile 2 folder. Right-click the OneDrive tray icon → Settings → Sync and backup → Manage backup**, and exclude the AppData/Roaming path. OneDrive locks Builds.bin for several seconds during upload, which the new serializer interprets as a deadlock.

1. Roll back to 0.4.x temporarily if your league character is unplayable. Right-click PoE 2 in Steam → Properties → Betas → 0.4.0-legacy. The 0.4 branch keeps your saves intact and lets you log in until your 0.5 hotfix arrives — switch back to none / default once 0.5.0c is confirmed installed.

If it still doesn't work

If the client still crashes after both updating to 0.5.0c+ and deleting Builds.bin, the next step is the full Logs\Client.txt from %AppData%\Path of Exile 2\Logs\ — the line starting BuildSerializer FATAL: deadlock at offset 0x... tells GGG support exactly which serializer chunk is failing. File a ticket at support.grindinggear.com with the log attached, your account name, and the character that triggered the crash. Include the output of dxdiag if you also see GPU-side errors.

For startup crashes on MSVCP140.dll, install the latest Microsoft Visual C++ 2015–2022 Redistributable (x64) from aka.ms/vs/17/release/vc_redist.x64.exe and reboot. The 0.5.0 build links against a newer CRT than 0.4 did, and older redistributables crash during the migration step. Players on Linux/Proton should switch to Proton Experimental 9.0-4 or later — earlier Proton builds segfault on the new serializer regardless of which hotfix is installed.