Hey all. My company is currently implementing GrowthBook, and we're seeing Multiple Exposures Issue for most of our sanity tests. Roughly 17% of all users are being filtered out due to this. This is happening in tests with no new phases, so I don't expect that Sticky Bucketing is the culprit here. I've been unsuccessful in finding a solution in the documentation. So far, in this section (https://docs.growthbook.io/kb/experiments/troubleshooting-experiments#solution-4-ensure-the-hash-attribute-and-identifier-type-match) I see this: "_When you analyze experiments, you set an "Identifier Type" that corresponds to columns in your data warehouse. Ideally, the Hash Attribute that you choose for users is both (1) logged to the data warehouse in the trackingCallback, and (2) is used as the "Identifier Type" for all of these experiments. By doing this, you establish a 1:1 relationship between the Hash Attribute and the Identifier Type."_ However, the documentation also states that if my Hash attribute doesn't correspond to the identifier in the data warehouse, I would see both Multiple Exposures AND SRM issues; I don't see SRM issues in my tests. Can anyone help recommend a way to debug or investigate the root cause of this issue?

Can you tell me more about what kind of experiment this is?

Hi @fresh-football-47124 It is basically any experiment we run. We are running a few sanity checking tests, where Control and Variation are entirely the same. It's a Visual Editor test with no visual or functional difference between variations (other than VAR printing a browser console msg). We see this issue pop up:

can you share the implementation code?

I'll reach out to my developer and get back to you 🙂

this can happen when the randomization unit is different from the analysis unit

My developer sent me this now: Config:

window.growthbook_config = window.growthbook_config || {};

window.growthbook_config.attributes = {

"visitorState": "Company",

"userIsLoggedIn": "foo",

"useQuarterlyBonus": "foo",

"PageTemplate": "foo",

"item_list_name": "foo",

"lomax_source": "foo"

};

window.growthbook_config.trackingCallback = function(experiment, result) {

if (typeof dataLayer !== 'undefined') {

dataLayer.push({

'event': 'growthbook_experiment',

'experiment_id': experiment.key,

'variation_id': result.key

});

}

console.log("GrowthBook experiment:", experiment.key, "variation:", result.key);

};

Script to fetch growthbook SDK:

<script async="" data-api-host="<https://cdn.growthbook.io>" data-client-key="sdk-lbJ8nntO3Byaw1y" src="<https://cdn.jsdelivr.net/npm/@growthbook/growthbook/dist/bundles/auto.min.js>"></script>

Loading chain: config -> script for sdk -> popup system js file

hi Kim

The randomization unit is

id

(v2 hashing). This is set via

growthbook_config.attributes

in the frontend code. It maps to

anonymous_id

in our GrowthBook assignment query, which corresponds to

user_pseudo_id

in BigQuery. We've been experiencing a multiple exposures issue (~17-19% of traffic) which we believe is caused by the SDK firing before

id

is available. I've attached a screenshot of the experiment. I'm also attaching the "SDK payload" from the DevTools extension.

{
  "status": 200,
  "features": {
    "test_gb_popup_full": {
      "defaultValue": false
    },
    "test_popup_local_lasse": {
      "defaultValue": true
    },
    "Sign-up_10": {
      "defaultValue": true
    },
    "test-oprette-feature": {
      "defaultValue": 1
    }
  },
  "experiments": [
    {
      "key": "gb-lomax-test1",
      "changeId": "bb07425a4e342efdb2b431af49b287f4f6f54ce5818e6a2230f71833d9db7656",
      "status": "running",
      "variations": [
        {
          "css": "",
          "js": "console.log(\"Control - yes!\")",
          "domMutations": []
        },
        {
          "css": "",
          "js": "console.log(\"V1 - yes!\")",
          "domMutations": []
        }
      ],
      "hashVersion": 2,
      "hashAttribute": "id",
      "fallbackAttribute": "",
      "disableStickyBucketing": false,
      "bucketVersion": 1,
      "minBucketVersion": 0,
      "urlPatterns": [
        {
          "include": true,
          "type": "simple",
          "pattern": "/*"
        }
      ],
      "weights": [
        0.5,
        0.5
      ],
      "meta": [
        {
          "key": "0"
        },
        {
          "key": "1"
        }
      ],
      "filters": [],
      "seed": "477fbeed-3a41-4add-9eed-f7299d0ed537",
      "phase": "1",
      "condition": {
        "url": {
          "$exists": true
        }
      },
      "coverage": 1
    },
    {
      "key": "test-i-kurv",
      "changeId": "96f03b870bdf983653b3087f680a3dea464030b2d7e82e7d8a7556e6131326e1",
      "status": "running",
      "variations": [
        {
          "css": "",
          "js": "",
          "domMutations": []
        },
        {
          "css": "",
          "js": "console.log(\"Kurv-test - yes!\")",
          "domMutations": []
        }
      ],
      "hashVersion": 2,
      "hashAttribute": "id",
      "fallbackAttribute": "",
      "disableStickyBucketing": false,
      "urlPatterns": [
        {
          "include": true,
          "type": "simple",
          "pattern": "<https://www.lomax.dk/kurv/>"
        }
      ],
      "weights": [
        0.5,
        0.5
      ],
      "meta": [
        {
          "key": "0"
        },
        {
          "key": "1"
        }
      ],
      "filters": [],
      "seed": "e7fffa7a-3834-409f-bbf0-a7fd498a31fc",
      "phase": "0",
      "condition": {
        "url": {
          "$exists": true
        }
      },
      "coverage": 1
    },
    {
      "key": "desktop-brugete",
      "changeId": "ea4622d0776248dfb7df6571a73451dcf39672f73f59e7e628bf6270c5ffd65a",
      "status": "running",
      "variations": [
        {
          "css": "",
          "js": "",
          "domMutations": []
        },
        {
          "css": "",
          "js": "console.log(\"forside test - VAR!\")",
          "domMutations": []
        }
      ],
      "hashVersion": 2,
      "hashAttribute": "id",
      "fallbackAttribute": "",
      "disableStickyBucketing": false,
      "bucketVersion": 1,
      "minBucketVersion": 0,
      "urlPatterns": [
        {
          "include": true,
          "type": "simple",
          "pattern": "<https://www.lomax.dk/*>"
        }
      ],
      "weights": [
        0.5,
        0.5
      ],
      "meta": [
        {
          "key": "0"
        },
        {
          "key": "1"
        }
      ],
      "filters": [],
      "seed": "5c5d60cf-e4d7-469a-aafb-1da4e488b725",
      "phase": "1",
      "condition": {
        "deviceType": "desktop"
      },
      "coverage": 1
    },
    {
      "key": "ny-sanity-test-efter-gtm-fix",
      "changeId": "ff1af3a16c1f98104dc33df6aced3e183e141c59d59df5e31913beeb5d6fbd79",
      "status": "running",
      "variations": [
        {
          "css": "",
          "js": "console.log(\"Control - yes!\")",
          "domMutations": []
        },
        {
          "css": "",
          "js": "console.log(\"Sanity-test V2 - VAR\")",
          "domMutations": []
        }
      ],
      "hashVersion": 2,
      "hashAttribute": "id",
      "fallbackAttribute": "",
      "disableStickyBucketing": false,
      "urlPatterns": [
        {
          "include": true,
          "type": "simple",
          "pattern": "/*"
        }
      ],
      "weights": [
        0.5,
        0.5
      ],
      "meta": [
        {
          "key": "0"
        },
        {
          "key": "1"
        }
      ],
      "filters": [],
      "seed": "477fbeed-3a41-4add-9eed-f7299d0ed537",
      "phase": "0",
      "condition": {
        "url": {
          "$exists": true
        }
      },
      "coverage": 1
    }
  ],
  "dateUpdated": "2026-03-31T05:40:36.120Z"
}

from what I can tell, you're assigning based on "id" but I don't see "id" set in your list of attributes

Ok. So how would I proceed from here?