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Fleack returns named, structured error codes so you can diagnose problems quickly without guessing. This page covers every error you can encounter — whether it surfaces in your mobile app, in the backoffice, during test setup, or in the lever wizard — and walks you through the fix for each one.

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Edge errors

These are the only Fleack errors that reach your mobile app. All other errors are contained to the backoffice or your internal tooling. 
{ "error": "tenant_not_found", "host": "<the host that was sent>" }
The hostname your app sent in the Host header didn’t match any tenant configured in Fleack. Fleack couldn’t identify which tenant should handle the request.
1

Verify DNS is pointing at Fleack

Check that your API subdomain resolves to a Fleack address. Run a DNS lookup for your hostname and confirm the result is the Fleack address you were given during setup.
2

Confirm the tenant route exists

Open the backoffice and go to Admin → Tenants. The host field on your tenant must match exactly what your app sends in the Host header — including subdomain.
3

Wait for the cache to refresh

If you recently added or updated the tenant, the gateway can take up to 10 seconds to pick up the change. Wait briefly, then retry.
{ "error": "origin_unreachable", "target": "<upstream URL>", "message": "..." }
Fleack successfully received your app’s request but couldn’t reach your real backend to forward it. The message field contains the underlying network error (for example ECONNREFUSED, ENOTFOUND, or ETIMEDOUT).
This is a fail-open scenario. From your app’s perspective it looks the same as if your backend had gone down without Fleack in the path. Your existing retry and offline-mode logic handles it normally — Fleack never introduces new failure modes.
1

Check your backend is reachable

Verify your real backend is up and responding. Try hitting your backend’s health endpoint directly from outside Fleack to confirm it’s available.
2

Check the upstream URL in your tenant settings

Open Admin → Tenants in the backoffice and review the upstream field. It must be the full URL of your real backend, including protocol and any path prefix.
3

Check IP allowlisting

If your backend restricts inbound traffic by IP, ensure Fleack’s egress IPs are on your allowlist. Contact contact@fleack.io for the current egress IP ranges.
4

Read the message field

The message value tells you exactly what failed at the network level. Start your investigation on the backend side based on that error.

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Backoffice errors

These errors appear in the Fleack backoffice UI or in API responses when your team manages tenants, members, and tests.
Your session has expired or wasn’t included in the request.Fix: sign back in. If you keep getting 401 immediately after logging in, email contact@fleack.io — this is typically a session configuration issue on Fleack’s side that your account operator can resolve.
A write operation (POST, PUT, PATCH, or DELETE) was sent without a valid CSRF token.Fix: the backoffice attaches the required x-fleack-csrf header automatically. If you see this error, your browser session is out of sync — refresh the page and try again.
You attempted to access an admin-only endpoint without super-admin privileges.Fix: super-admin is a single role granted during account provisioning. You cannot escalate to super-admin from the UI by design. If you need this level of access, contact contact@fleack.io or the person who provisioned your Fleack account.
You tried to invite someone who is already a member of the organisation or already has a pending invitation waiting.
1

Check the Members page

Open Members in the backoffice. If the person is already listed, no further action is needed.
2

Clear a stuck invitation

If they have a pending invitation they haven’t accepted, go to the Invitations tab, revoke the existing one, then send a fresh invite.
The invitation link is older than its validity window: 7 days for standard invitations, 14 days for owner invitations.Fix: ask an admin or owner to issue a new invitation from the Members page.

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Test issues

These aren’t error codes — they’re situations where a test appears to be running but something about the data doesn’t look right.
The most common cause is a mismatch between the endpoint_signature the test is bound to and the signature of the requests your app is actually making.
1

Check the endpoint signature on the test

Open the test detail page and note the endpoint_signature it’s bound to.
2

Find that signature in the Endpoints catalog

Go to Endpoints in the backoffice and look for that exact signature. If it’s not listed, your app hasn’t hit that path recently enough for Fleack to have seen it.
3

Look for similar signatures

If you see signatures that look similar but have different query parameters, you may have created the test against an older signature. Recent versions of Fleack strip filter, sort, and pagination query keys from signatures — but a test created before that change stays bound to the old signature. Recreate the test against the current signature.
This is expected and correct behaviour. The Levers catalog shows the value your backend actually returns — a snapshot taken before any variant injection. Fleack is still injecting the variant value for users in the test group.
To verify injection is working, make a request directly to your tenant URL with a matching User-Agent header from a clean IP. Check the response body — you should see the variant value if that user falls into the test group.
There are two distinct causes:Anonymous traffic. The exposed_users counter only increments for exposures with a non-null user identity — a user-id header, an authenticated path, or a UA + IP fallback (available in recent Fleack versions). If you’re on an older Fleack version that returned null for anonymous users, contact contact@fleack.io to arrange an upgrade.The target path is missing in some responses. Variant injection only fires — and an exposure is only logged — when Fleack can find the target_key in the response body. If your backend returns different response shapes for some requests and the targeted path is absent in those responses, those requests won’t produce an exposure. Check the test’s target_key against your actual response body to confirm the path always exists.

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Lever wizard issues

The wizard found no endpoints with captured body samples. This means either no traffic has passed through your tenant yet, or all requests so far returned non-JSON content (HTML, binary, etc.).Fix: exercise your app so that real traffic flows through the Fleack tenant, then refresh the wizard. Any JSON-returning endpoint will appear once Fleack has seen at least one response from it.
The endpoint’s most recently captured response had no leaf scalar values that Fleack could surface as a lever. This is common when the response is a list of objects ([{...}, {...}]) without nested scalars, or when the response body is empty.
1

Confirm the endpoint returns the value you want to test

Check your backend — make sure the parameter you want to experiment on (for example data.config.gems_reward) is actually present in the response body.
2

Inspect the captured sample in the backoffice

Open the endpoint in the backoffice and review its captured sample. You’ll be able to see exactly what body Fleack last recorded.
3

Contact support if the value is there but not surfaced

If the scalar exists in the captured body but the wizard still doesn’t show it, email contact@fleack.io with the endpoint signature and the response body. We’ll fix the scalar walker.

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Health check endpoints

Each Fleack service exposes a health endpoint you can poll for liveness probes or quick diagnostics.
ServiceEndpointWhat it shows
GatewayGET /_flick/healthtenants_count and the current tenant host registry
Tenant serviceGET /_flick/healthevents_count, active_tests, and database connectivity
Control-planeGET /healthDatabase connectivity and AI integration status
If a tenant’s health endpoint shows active_tests: 0 despite a running test in the backoffice, the cache hasn’t refreshed yet. Wait 5–10 seconds and check again. If it stays at 0 after 30 seconds, contact contact@fleack.io with your tenant_id.

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Still stuck?

Email contact@fleack.io with:
  • The error code or a description of the symptom (a screenshot helps)
  • The relevant endpoint_signature and tenant_id
  • The approximate timestamp so we can locate the event in logs
We respond within one business day.