Quick answer: Addressables > Build > Clean Build > All rebuilds from scratch. Delete Library/com.unity.addressables/aa if cleans still misbehave. For CI, always do Clean Build; for dev iteration, incremental is fine.

Here is how to fix Unity Addressables build cache corrupt. You change a few assets, build Addressables, and the test build still shows the old version of a sprite. Or a new asset you added is missing despite being marked Addressable. The Addressables cache is an intricate beast — it tracks asset dependencies, groups, and serialized bundles, and when something goes wrong the symptoms are confusing.

The Symptom

Addressables builds produce incorrect or stale content:

What Causes This

ScriptableBuildPipeline (SBP) cache stale. Addressables uses SBP to build AssetBundles. SBP caches computed dependencies and hashes. If the cache becomes inconsistent — for example, after a git pull that changes files without updating mtime — incremental builds can miss changes.

Library/com.unity.addressables/aa corrupt. The Addressables runtime cache in Library. If this gets corrupted (Unity crash during build, disk issue), subsequent builds reference stale data.

Group settings changed but not applied. Changing a group’s build path, load path, or compression settings requires a Clean Build to take full effect. Incremental builds apply settings inconsistently.

content_state.bin stale. Update a Previous Build uses this file as a snapshot. If you lost or modified it, Update builds reference a different baseline than expected, producing incorrect delta bundles.

Schema changes. Modifying Addressable schema (addressable key types, custom data) can invalidate cached bundle data. Rebuild full after any schema work.

The Fix

Step 1: Clean Build. Open Window > Asset Management > Addressables > Groups. In the window menu, choose Build > Clean Build > All. Then Build > New Build > Default Build Script.

This clears the SBP cache and rebuilds every bundle. Slow (minutes, even on small projects) but authoritative. Use as your first debugging step for any inconsistency.

Step 2: Nuke the cache directory. If Clean Build still produces bad output:

# Close Unity first
rm -rf Library/com.unity.addressables
rm -rf Library/BuildCache

Reopen Unity. Let it reimport. Rebuild Addressables from scratch. This is the nuclear option but guaranteed to clear any corruption.

Step 3: Always Clean Build in CI. Incremental builds are fine for local iteration but introduce non-determinism in CI. Your build server should always start from a clean state.

// In a CI build script
using UnityEditor.AddressableAssets.Settings;

public static class CIBuild
{
    public static void BuildAddressables()
    {
        var settings = AddressableAssetSettingsDefaultObject.Settings;
        AddressableAssetSettings.CleanPlayerContent(settings.ActivePlayerDataBuilder);
        AddressableAssetSettings.BuildPlayerContent(out var result);
        if (!string.IsNullOrEmpty(result.Error))
            throw new Exception(result.Error);
    }
}

This function: (1) cleans, (2) builds fresh, (3) fails loudly on errors. CI should not allow silent Addressables failures.

Step 4: Preserve content_state.bin for Update builds. If you ship live content updates, the content_state.bin produced by the initial build is your baseline. Check it into source control (large file, use Git LFS). Each live patch runs “Update a Previous Build” against this baseline.

Losing the baseline means you cannot do delta patches — every update becomes a full rebuild with potentially different bundle hashes, breaking cached content on players’ devices.

Profile Chaining Issue

Addressables supports multiple profiles (Dev, Staging, Production) with different paths. Switching profiles in the editor sometimes does not refresh the build configuration. Always do a Clean Build after switching profiles, at minimum.

Group Schema Checks

Inspect each Addressable group. Common mistakes:

Use Window > Asset Management > Addressables > Analyze to run built-in diagnostics. Check Rules to catch duplicate dependencies, bundle size issues, and misconfigurations.

When All Else Fails

Back up your Addressables group assets. Delete the entire Addressables folder (Assets/AddressableAssetsData). Reinstall the Addressables package. Recreate groups from scratch using the backed-up settings. Rebuild. Heavy but guaranteed to reset everything.

Understanding the issue

Build pipelines transform development assets into shipping packages. Each transformation can introduce subtle changes: compression, stripping, format conversion, code generation. A bug that only appears in the cooked build is usually one of these transformations doing something the author didn't expect.

The specific bug described above is the kind that surfaces during integration rather than unit testing. It depends on a combination of factors: the asset configuration, the runtime state, the platform's specific behavior. In isolation, each piece looks correct; in combination, the bug emerges. This is why thorough integration testing - playing the actual game in realistic conditions - catches things that automated tests miss.

Why this happens

Bugs of this class are particularly easy to ship past internal QA because they often depend on specific runtime conditions - hardware combinations, network states, or asset configurations that QA didn't reproduce. Players hit them in the wild, file reports that are hard to repro, and the bug accumulates negative reviews while engineering tries to recreate the failure mode.

At the engine level, the behavior comes from a deliberate design decision in Unity. The engine team chose a particular trade-off - usually performance versus convenience, or generality versus specificity - and that trade-off has consequences when you push against it. Understanding the trade-off is what turns 'this bug is mysterious' into 'this bug is the expected consequence of this design'.

Verifying the fix

For shipping games, the safest verification is a staged rollout. Apply the fix to 1% of players for 24 hours; watch the affected metric; expand if green. Skipping the staged rollout means the verification is the entire player base, which is too high a stakes for most fixes.

Reproducibility is the prerequisite for verification. If you can't reliably reproduce the bug pre-fix, you can't reliably verify it post-fix. Spend time getting a clean reproduction before you write any fix code. The fix is fast once you understand the reproduction; the reproduction is the slow part.

Variations to watch for

There's almost always a less obvious case where the same problem applies. The reported case is the one a player hit; the related cases hide because they're rarer or affect fewer players. After fixing the reported case, search the codebase for the pattern - one fix often unlocks several.

Adjacent bugs often share a root cause. After fixing the case you've found, spend an hour searching the codebase for similar patterns. What's the same call with different arguments? The same data flow with a different entity type? The same lifecycle issue in a sibling system? Each match is a candidate for the same fix, or a related fix that prevents future bugs of the same class.

In production

Live games surface this bug class at scale. What's a rare edge case in development becomes a daily occurrence once you have a few thousand concurrent players. The class isn't 'this player has a unique setup'; it's 'one in N thousand sessions will trigger this exact combination'.

When triaging a similar issue in production, prioritize gathering data over hypothesizing causes. A player report describes a symptom; what you need is a build SHA, a session timestamp, and ideally a screen recording or session replay. With those, the bug becomes tractable. Without them, you're guessing at hypothetical reproductions that may not match what the player actually hit.

Performance considerations

If this issue manifests under high load (many actors, many particles, many network connections), profile the post-fix code path with realistic counts. The original cost was a bug; the new cost is real work, and real work has a budget.

Diagnostic approach

The diagnostic tools available depend on your engine and platform. Use the engine's native profilers and debug overlays before reaching for external tools. The native tools have context that external tools lack - they know which subsystem owns the code, which assets are loaded, and what state the engine is in.

For Unity-specific diagnostics, the editor's profiler is the canonical starting point. Capture a representative frame with the symptom present; compare against a frame without the symptom; the diff often points directly at the cause. If the symptom is non-deterministic, capture multiple frames and look for the pattern - the cause is usually a state transition or a specific input value rather than a continuous effect.

Tooling and ecosystem

The tooling around this bug class matters as much as the fix itself. Good logging, accessible profilers, and clear error messages turn 30-minute investigations into 5-minute ones. If your project doesn't have visibility into this code path, the first fix should add the visibility - the second fix uses it.

Within Unity, the relevant diagnostic surfaces include the standard frame debugger, memory profiler, and engine-specific debug overlays. Each one shows a different facet of what's happening. The frame debugger reveals draw call ordering and state transitions; the memory profiler shows allocation patterns; the debug overlay reveals per-system state. Bugs that resist one tool usually surrender to another - the trick is knowing which tool to reach for first.

Edge cases and pitfalls

Platform-specific edge cases are worth enumerating explicitly. iOS handles backgrounding differently than Android; Windows handles focus changes differently than macOS. A fix that works on the development platform may not work on every target. Test on each shipping platform deliberately.

When writing a regression test for this fix, focus on the boundary conditions that surfaced the original bug. Tests that exercise the happy path catch obvious regressions; tests that exercise the boundary catch the subtler regressions that look like new bugs but are really the original returning. The latter are the tests that earn their keep over the long life of the project.

Team communication

Document the fix and its rationale in the commit message or attached engineering doc. Future engineers will encounter related issues; the rationale tells them whether your fix is reusable or specific to the case at hand. Without rationale, the fix gets reverted or copied incorrectly.

If this fix touches a system several engineers work in, a short writeup in the team's engineering channel helps. Not a full design doc - a paragraph explaining what was wrong, what's fixed, and what to watch for. Future engineers encountering similar symptoms will search for the fix; making it findable is a small investment that pays back later.

“Addressables is fast when it works. When it does not, Clean Build is your reset button. Use it before anything else.”

Related Issues

For general Addressables load failures, see Unity Addressables Failed to Load. For memory-related issues, Addressables Memory Not Releasing covers runtime cache leaks.

Clean Build first. Cache directory second. Profile last. Debug in that order.