GTM Errors

Browser Console Errors

1. Failed to load resource: the server responded with a status of 404 (Not Found)
   • Occurs if the GTM container script or dependent scripts (e.g., analytics.js) cannot be loaded.
2. Uncaught ReferenceError: gtag is not defined
   • Triggered when the gtag function is called but the necessary libraries haven’t been loaded.
3. Uncaught SyntaxError: Unexpected token
   • Indicates a syntax error in custom JavaScript added to GTM.
4. Refused to execute script from 'https://www.googletagmanager.com/...' because its MIME type ('text/html') is not executable
   • Happens if the server or CSP misidentifies the GTM script.
5. Refused to load the script ... because it violates the following Content Security Policy directive
   • A strict CSP policy is blocking GTM scripts.
6. Uncaught TypeError: Cannot read properties of undefined (reading 'X')
   • Commonly occurs if a JavaScript variable or DOM element expected by GTM is missing or undefined.
7. A cookie associated with a cross-site resource at <domain> was set without the SameSite attribute
   • Indicates an issue with cookie handling, especially in cross-domain tracking setups.

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GTM Preview Mode Errors

1. No tags were fired.
   • Indicates that no tags matched the firing conditions during a user action.
2. Tag blocked by a trigger.
   • A trigger’s conditions actively prevent a tag from firing.
3. Tag is not firing due to consent settings.
   • Seen when GDPR or CCPA consent is not obtained for certain tags.
4. Tag not fired: X (Script not allowed).
   • Occurs if scripts are blocked by a site’s security policies or third-party extensions.
5. Error: Container does not match this site.
   • Happens if the container ID used in GTM does not match the website’s container.
6. Error establishing connection to the tag assistant preview server.
   • Indicates an issue connecting GTM Preview Mode to the Tag Assistant.

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Google Analytics Errors via GTM

1. Measurement Protocol requests are not matching.
   • Happens if the data sent through GTM does not match Google Analytics configurations.
2. GA4 Configuration tag is missing.
   • Occurs if the necessary GA4 configuration tag hasn’t been set up.
3. Duplicate hit detected.
   • Seen when the same event is tracked multiple times, often due to duplicate GTM triggers.
4. Invalid event parameter
   • Indicates a mismatch between the event parameters sent and what GA expects.

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Network Errors

1. net::ERR_BLOCKED_BY_CLIENT
   • Indicates that a browser extension (e.g., ad blockers) is preventing GTM or analytics scripts from loading.
2. Failed to load https://www.googletagmanager.com/gtm.js: net::ERR_INTERNET_DISCONNECTED
   • Suggests a connectivity issue preventing GTM scripts from loading.
3. Status Code: 403 Forbidden
   • Indicates that the GTM container script is restricted, possibly due to incorrect permissions or regional limitations.

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Consent and Privacy Errors

1. Consent mode configuration error.
   • Indicates that GTM’s consent mode is misconfigured or not supported by certain tags.
2. GTM Error: No consent was provided for this tag.
   • Seen when GDPR/CCPA consent is not granted for a specific action.

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Other Common Errors

1. GTM script not found
   • Occurs when the GTM container ID is missing or incorrectly embedded on the website.
2. Blocked a frame with origin ... from accessing a cross-origin frame.
   • Indicates a cross-origin issue that can arise during debugging in Preview Mode.
3. GTM cannot execute due to insufficient permissions.
   • Happens if the GTM container permissions are misconfigured, such as limited access for a collaborator.
4. Error loading container: timeout
   • Occurs if GTM fails to load within the allowed time due to network or server latency.

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Understanding these error messages can help pinpoint specific problems with your GTM setup and guide effective troubleshooting steps.