Debugging GAS¶

Open the console and run showdebug abilitysystem. Look at the Granted Abilities list. Is your ability there?

• Not listed — the ability was never granted. Check that it's in your character's StartupAbilities array, or that GiveAbility() is being called at runtime.
• Listed — move to Step 2.

Check your ability's Activation Blocked Tags in its Class Defaults. Then check showdebug for the owner's current tags. If the owner has any of the blocked tags, the ability can't activate.

Common culprits: State.Dead, CrowdControl.Hard.Stun, a leftover tag from a previous ability that didn't call EndAbility.

Check showdebug → Active Effects. If you see the cooldown GE still active, the ability is still on cooldown. Check the cooldown duration — is it longer than expected?

Also check: does the cooldown GE actually grant a Cooldown.* tag? Without the tag, GAS doesn't know the ability is on cooldown.

Check the relevant attribute value in showdebug → Attributes. If Stamina is 3 and the cost is 5, the ability fails silently.

• ServerOnly abilities won't activate on clients
• LocalOnly abilities won't activate on the server
• LocalPredicted is the most common choice for player abilities

Filter for LogAbilitySystem in the Output Log. GAS logs activation failures with reasons. Common messages:

• "Can't activate LocalOnly or LocalPredicted ability when not local" — wrong net role
• "Can't activate ability because tags are blocked" — tag check failed
• "Cost check failed" — not enough resources

Check showdebug → Active Effects. For Instant effects, they won't appear here (they execute and disappear). For Duration/Infinite effects, they should be listed.

If it's not listed, the effect was never applied — check the ability's ApplyGameplayEffectSpec call.

Open the GE Blueprint and verify the modifier's Attribute field matches your actual AttributeSet class name exactly. MyAttributeSet.Health is different from OtherAttributeSet.Health.

• SetByCaller: Check the Output Log for "SetByCaller tag not found". This means the ability didn't call SetSetByCallerMagnitude with the matching tag.
• Scalable Float: Is the value actually set? A default of 0 does nothing.
• Attribute-Based or MMC: Add logging to your calculation class.

Individual modifiers can have source/target tag requirements. If the source ASC or target ASC doesn't have the required tags, the modifier is skipped silently.

If the target doesn't have the attribute you're modifying, nothing happens — no error, no crash, just silence. Verify the target has an ASC with the right AttributeSet.

The cue Blueprint's Gameplay Cue Tag must exactly match the GameplayCue.* tag on the effect or the tag passed to ExecuteGameplayCue. Case-sensitive, hierarchy matters.

Check the Output Log for "missing gameplay cue" warnings. The GameplayCueManager scans specific paths — your cue Blueprint might be in a folder it doesn't scan. Check Project Settings → Gameplay Cues → Paths.

Cues can be lazy-loaded. If the cue hasn't been loaded yet when the effect fires, it won't play on the first trigger. Check Lazy Loading settings.

ShouldSuppressGameplayCues can be overridden to conditionally suppress cues. Also check if this is a local-only cue firing on a non-local client — replicated cues go through the server.