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Experiment Not Running

You published an experiment but visitors are not being bucketed into variations — the results page shows zero visitors, or you cannot see the variation when you visit the page yourself. This guide walks through every reason this happens and how to fix each one.

Symptoms

  • The results page shows 0 visitors after several hours.
  • You visit the target page but do not see any variation applied.
  • Calling avsb.getVariation('exp_id') in the console returns null.
  • The variation CSS/JS does not appear to be injecting into the page.

Checklist

1

Check the experiment status

Open the experiment in A vs B. The status badge at the top should say Running. If it says:
  • Draft — the experiment has not been published yet. Click Publish experiment on the Step 4 (Review) page.
  • Paused — the experiment was running but has been manually paused. Click Resume to start it again.
  • Completed — the experiment has been stopped. You would need to create a new experiment or contact support to reopen it.
2

Confirm the snippet is installed and detected

Go to Project Settings → Snippet. The status badge should show Snippet detectedin green. If it shows "Not detected", the snippet is not installed correctly and no experiments will run. See Snippet Not Detected for the full fix guide.
3

Check the targeting rules

Open the experiment and click on Step 1 – Targeting to review the URL rules.
  • Is there at least one URL rule configured? An experiment with no URL rules will never match any page.
  • Does the URL rule actually match the page you are testing on? Test your rule by comparing it to the browser's address bar. For example, a rule of /pricing with Exact match will only trigger on exactly /pricing — not /pricing/ (with a trailing slash) or /pricing?plan=pro (with a query string).
  • Consider using Substring match if you want the experiment to match a path regardless of query strings or trailing slashes.
4

Check audience conditions

If you have added audience conditions (Step 1 → Audiences), they filter which visitors are eligible. A visitor must match all conditions to be included. Check whether the conditions match the visitor profile you are testing with. Common mistakes:
  • A segment condition is set (e.g. "plan = premium") but the visitor does not have that segment set.
  • A device condition excludes the device you are testing on (e.g., "device = desktop" but you are on mobile).
To test without audience filtering, temporarily remove all audience conditions, test, then re-add them.
5

Check traffic allocation

Open Step 2 – Variations. Each variation has a traffic percentage. The sum of all variations must be greater than 0% for the experiment to receive any traffic. If all variations are set to 0%, no visitors will be bucketed. Also check the experiment-level traffic allocation — if this is set to a very low percentage (e.g. 1%), most visitors will be excluded from the experiment entirely.
6

Check the browser DevTools console for errors

Visit the target page and open DevTools → Console. Look for any errors that start with [avsb] or relate to the snippet. A JavaScript error in the variation code itself can cause the experiment to silently deactivate for that visitor.
7

Try forcing a variation to verify injection works

Open DevTools → Console on the target page and run:
javascript
1// Replace with your actual experiment ID and a variation ID
2const success = avsb.forceVariation('exp_abc123', 'var_xyz789');
3console.log('Force result:', success);
If this returns true and you see the variation applied, the experiment engine is working — the issue is with targeting or audience conditions. If it returns false, the experiment may not be in the datafile yet (give it a minute after publishing) or the IDs are wrong.
Info
After publishing an experiment, there may be a delay of up to 60 seconds before the experiment appears in the datafile that the snippet downloads. Try refreshing the page and testing again after a short wait.

Inspecting the datafile

The snippet downloads a JSON datafile containing all running experiment configurations for your project. You can inspect it directly:

  1. Open DevTools → Network tab.
  2. Reload the page.
  3. Filter by "datafile" or look for a request to cdn.avsb.cloud/datafile/.
  4. Click the request and look at the Response tab. Search for your experiment ID. If it is not in the JSON, the experiment may not have been published yet, or the datafile is cached.
Hard refresh to bypass the cache
The snippet's datafile is cached in the browser for performance. If you just published a new experiment and it does not appear to be running, try a hard refresh (Ctrl+Shift+R on Windows/Linux, or Cmd+Shift+R on Mac) to bypass the cache and download the latest datafile.