reznok/gmcabilitysystem/gmas-debug

Behavior below was verified against GMC 2.3.x and GMAS 1.4. Confirm signatures in this project's own headers (paths are relative to each plugin's root, e.g. Source/GMCCore/Public/Components/GMCReplicationComponent.h); GMC's source is not part of this plugin.

A GMAS fault is almost always one of three things: the two sides of a move disagreed (a correction and a replay), an operation did not reach the move it was meant for (dropped or forced), or something ran on a replayed or combined move that should have run once. This skill lists the places where GMAS and GMC show that, a procedure that separates the three, how a healthy activation reads in the log, and a symptom table: references/symptoms.md. The rules the symptoms violate live in gmas:gmas-rules and gmas:gmc-prediction; the networked test setup in gmas:gmas-testing. GMAS paths below are relative to Source/GMCAbilitySystem/.

Surfaces

Log categories. Raise one with Log <Category> Verbose in the console (VeryVerbose for the per-move lines), -LogCmds="LogGMCAbilitySystem Verbose" on the command line, or [Core.Log] in DefaultEngine.ini. All default to Log.

Trace tags (1.4+). Bracketed prefixes in LogGMCAbilitySystem lines (Private/Components/GMCAbilityComponent.cpp, Private/Ability/GMCAbility.cpp, Private/Ability/Tasks/GMCAbilityTaskBase.cpp). op is the operation id: negative for client-made operations, positive for server-made ones; move_ts is the move timestamp, identical on both machines for the same move.

Untagged lines worth knowing, same category: RPCOnServerOperationAdded: N (Verbose, the owner received a server operation), Forcing Operation On Server (Verbose, the grace expired and the server applied the operation outside the move; one frame after the call for AI and unpossessed pawns), Activation operation N already consumed on this side (redelivery/replay) — skipped (Verbose, a replay re-delivering an activation that already ran), Ability Activation for Ability.Dash Stopped By Cooldown / ... Stopped By Cost (1.4.1+) / ... Failing PreExecution check / ... Blocked By Other Ability / ... Stopped by an OnAbilityActivated listener (1.4.1+) / ... Stopped By Tags (Verbose, a refused activation; Stopped (Already Instanced) at VeryVerbose), Input tag not granted: X / Input tag not in the ability map: X (Warning, 1.4.1+; Ability Tag Not Granted / Ability Tag Not Found before), Effect X Not Confirmed By Server (ID: N), Removing... (Error), Dropped client operation N: payload expired after M moves (Warning), No Abilities Granted for InputTag (Error), Client attempted to apply server-auth event (Warning), Client operation type X is not allowed by server as client input (Error), X is deprecated ... Reported once. (Warning, 1.4.1+: a deprecated function was called, once per component). GMAS <version> loaded (Log, 1.4.1+) is the module's version line; on 1.4.0 it was the [GMAS-LIVE-CHECK] Module loaded banner at Warning.

Console (1.4+, `Private/Components/GMCAbilityComponent.cpp`, not in Shipping builds).

GMC console variables. Full table, with the GMC .cpp files that define them: gmc-diagnostics.md. The five that matter most for GMAS work:

Gameplay Debugger. The runtime module registers category GMCAbilitySystem (Private/GMCAbilitySystem.cpp, slot 9, enabled in game and simulate). Open the debugger with its activation key (' by default, an engine setting) and enable the category. For the debugger's selected actor it prints the server's data pack ([server]) and the local component ([client]) for granted abilities, active abilities, bound active tags, client-auth tags (1.4+), attributes, active effects (1.4.1+: one ToString() line each, with its state and the client's answer for its id: Pending, Validated, Timeout, or Authority on the server; 1.4.0 never showed the answer) and cached operation payloads (1.4+); a row whose count differs between the two is marked [INCOHERENCY] in red. 1.4.0 also had an Active Effects Data row that printed UNDER CONSTRUCTION; 1.4.1 removed it. On a listen server the server rows are read from the movement component's server state, so the host's own pawn shows its authoritative view.

Project Settings → GMC Ability System (1.4+), stored in DefaultGame.ini: