During the Diablo 4 Season 4: Loot Reborn Public Test Realm, which ran from April 2 to April 9, 2024, players hit a bug with the Kyovashad "Boost me to level 100" NPC. The boost did its primary job, but if you had already upgraded Aspects in your Codex of Power, it silently wiped those upgrades account-wide. Blizzard documented the bug and a workaround within days; the fix landed before the live patch 1.4.0 release on May 14, 2024, so the issue never reached live servers. This article is the historical archive.
For active D4 services on the current season, the live catalogue is at the live Diablo 4 hub.
With the takeaways framed, the bug itself is best understood as an order-of-operations problem between two new systems.
The PTR for Loot Reborn introduced two systems that interacted badly: the new Codex of Power upgrade tree (where farmed Aspects could be permanently improved beyond their drop roll) and the dedicated Kyovashad NPC that boosted a character straight to the lvl 100 cap for testing. The interaction the bug exposed was an order-of-operations problem.
If you first upgraded any Aspect in your Codex, then boosted any character on the account to level 100 through the NPC, the boost call's account-side reset cleared every upgrade on every Aspect, on every character. Aspects you had farmed and improved went back to their unupgraded baseline. Boosting an alt counted the same as boosting the main — the wipe ran on the account, not the character.
With the trigger pinned down, the practical fix during the PTR week was an order-of-operations workaround Blizzard surfaced through Wowhead.
Wowhead's PSA from April 3, 2024 carried Blizzard's recommended workaround: boost every character you wanted at level 100 BEFORE you upgraded any Aspects. Once all your alts were already boosted, the NPC's account-side reset had nothing to wipe, and you could move on to Codex upgrades safely.
This was a PTR-only constraint. Testers who wanted to evaluate the new Codex tree in earnest needed the workaround; testers who only wanted to play with the lvl 100 NPC for build experimentation could skip the workaround and just accept the resets.
Blizzard patched the interaction before Loot Reborn went live as Patch 1.4.0 on May 14, 2024. Live-server players never saw the bug. The live Codex of Power upgrade system shipped clean; the Tree of Whispers integration and Iron Wolves reputation system that defined Loot Reborn launched without the PTR's reset bug attached.
Loot Reborn (Season 4) was the patch that reshaped D4's loot system around itemization quality of life: Greater Affixes, tempered modifiers, and Masterworking all entered the live game with 1.4.0. The Codex of Power upgrade tree was a piece of that broader itemization rework — farmed Aspects became permanent character investments rather than disposable extracts.
The D4 timeline since: Season 5 (Infernal Hordes), Season 6 + Vessel of Hatred expansion (Oct 2024, level cap dropped 100 to 60), Season 7-13, with the live season now Season 13 Lord of Hatred. To compare current Aspect mechanics against the original Codex-upgrade design that this PTR introduced, compare current Diablo 4 builds.
No. The bug was PTR-only during the Season 4: Loot Reborn PTR window of April 2-9, 2024. Blizzard fixed the interaction before the patch went live on May 14, 2024, so production accounts were not affected.
Boost every character to level 100 through the Kyovashad NPC FIRST. Once all alts were already boosted, the account-side reset had nothing to wipe, and you could safely upgrade Aspects in your Codex of Power afterward.
No. The 100 cap was the original D4 cap and still applied during the Season 4 PTR. With Vessel of Hatred in October 2024, the live cap dropped to 60. On April 28, 2026 it rose to 70, which is where it sits in the current Season 13 (Lord of Hatred).
The upgrade tree let you spend farmed Aspect copies and resources to permanently improve an Aspect's baseline values stored in your Codex. The improved version became the new floor for any time you stamped that Aspect onto gear — making farmed Aspects a permanent character investment rather than something extracted and applied once.
Patch 1.4.0 (Season 4: Loot Reborn) launched on May 14, 2024, five weeks after the PTR closed. The Codex of Power upgrade tree, Greater Affixes, tempered modifiers, Masterworking, the Tree of Whispers Iron Wolves reputation system, and the Pit of the Artificers all shipped together.
Not at this scale. Subsequent PTRs have had their own bug lists, but the specific "boost-resets-Codex-upgrades" interaction was a one-time fault tied to the original Codex tree introduction. The current Codex (post-Vessel of Hatred rework) has a different account-storage model.
Two reasons. First, the original article is one of the early datapoints for how Blizzard handled D4 PTR-only issues — the archive preserves the timeline. Second, the Codex of Power upgrade mechanic still exists today (in a modified form), and the Season 4 PTR is when that mechanic first appeared. Knowing the origin point helps when comparing live behaviour against the original design.
