GTM Setup Errors And Solution Guide To Fix (Part 1)

Google Tag Manager (GTM) is a robust tool designed to manage tags and tracking codes across both websites and mobile applications. It serves as a centralized tag management system that enables the deployment of multiple tracking codes and facilitates data sharing with platforms like Google Analytics, Google Ads, SA360, Facebook/Meta, Snapchat, and many others.

However, during GTM implementation, some key features may be overlooked or underutilised, which can lead to tracking issues or inefficient setups. Many businesses encounter common mistakes during the GTM setup process that compromise the accuracy and effectiveness of their tagging strategy.

We’ll walk you through some of the most common Google Tag Manager (GTM) mistakes and provide practical, step-by-step tips to help you prevent them. Let’s explore each one in detail.

1. Using Static Values Instead of Constant Variables

Hardcoding values directly into tags results in disorganized tracking, increases the effort required for future updates, and raises the risk of errors.

Example: Adding GA4 Measurement ID directly into a tag.

GA4 ID configured as hardcoded

Best Practice: Always use constant variables for values which will not change frequently like IDs or configuration settings to ensure consistency.

For eg. Using constant variables for your measurement ID promotes uniformity throughout your tags and allows you to update the ID in one place, which improves efficiency in execution.

GA4 ID in a constant variable

2. Making Changes to the Default Workspace

Using the default workspace in Google Tag Manager for updates can result in conflicting changes when multiple stakeholders are working simultaneously. This not only disrupts collaboration but also increases the risk of errors and overwrites.

Changes to Default workspace

Best Practice: It is recommended to create a separate workspace with a clear and descriptive name while implementing any changes. This practice ensures safer collaboration, better version control, and easier review before publishing.

Creating dedicated workspaces allows for structured development, minimizes conflicts, and provides a cleaner audit trail for changes made.

Dedicated workspace for the changes

3. Using Raw HTML Instead of Tag Template

Not using Tag templates and in GTM multiple Custom JavaScripts written directly within HTML tags instead, it increases the size of your Tag Manager file, which may negatively impact your website's performance.

Custom HTML

Best Practice: Use the default or custom available tag templates provided by GTM for affiliate or third party platforms like Google Ads, Meta Pixel, LinkedIn, Floodlight, and others. These templates are lightweight, secure, and maintained by Google or trusted providers.

Usage of tag template

4. Using Multiple Trigger Conditions

Setting up multiple triggers or conditions for similar pattern events can make the GTM setup bulky and harder to manage. It also introduces redundancy and errors when changes are needed across similar triggers.

Example: One tag should fire for below pages of the website:

• One trigger: pricing
• One trigger: pricing-us
• One trigger: pricing-intl

Multiple triggers created

Best Practice: Use Regular Expressions (regex) in Custom Event Trigger to combine similar patterns into a single, efficient trigger. This reduces redundancy, simplifies updates, and improves performance.

Use a single regex-based trigger like:

Use of regex in the triggers

5. Mismatch Between DataLayer Push and Trigger Variable Name

Sometimes, the variable name used in GTM doesn't match the parameter name defined in the dataLayer object. This mismatch can prevent the trigger from firing correctly.

Example: At the time of login, If dataLayer object is pushing below event:

In your GTM, the variable for the User ID is set as “userId” instead of “user_id”, it won't pick up the value due to incorrect dataLayer key, that is leading to inaccurate or failed tag execution.

Best Practice:  Always ensure that the dataLayer variable name in GTM, exactly matches the key used in the dataLayer.push() method, in this case, use "user_id" if that’s the key defined in dataLayer.
GTM variable names are case-sensitive and must align precisely with the structure of the dataLayer.

6. Using Inconsistent Naming Conventions

Using inconsistent or unclear naming conventions in GTM can create confusion about the purpose of the tag, which namings should be followed in future and making the setup harder to manage to scale in future.

Inconsistent tag naming conventions

Best Practice: Adopt clear, consistent, and descriptive naming conventions for all GTM elements (Tags, Triggers, Variables). This keeps your setup organized, structured and understandable.

Use lowercase letters, separate words with underscores “_”, and include key identifiers like the event name and platform.

Example: For GA4 tag that tracks when someone clicks a subscribe button, use a name like: “subscribe_click_GA4” and similar for triggers, variables.

Comprehensible tag naming conventions

7. Not Removing Unused Elements

Unused tags, triggers, and variables clutter your GTM container and can lead to confusion and inefficiencies. It can majorly impact the load of the website and its performance

Best Practice: Regularly audit your GTM container and remove any unused/deprecated/no longer needed tags, triggers, and variables.

Example: There are tags without triggers, variables not linked to any entity, and long-paused tags no longer needed, to keep your setup clean, efficient, and easy to maintain.

Unused Triggers in GTM

8. Not Labelling Container Versions

Not labeling your container versions makes it hard to track history changes, troubleshoot issues, or roll back to a specific version when needed.

Not labelling container Versions

Best Practice: Always label each container version with a clear, descriptive name that reflects the changes made. This improves version controlling, aids in auditing and debugging, and makes collaboration easier for all stakeholders.

Labeled container versions

9. Tags Functioning on Desktop Web & Not on Mobile Web (MWeb)

Triggers often function seamlessly on desktop web platforms, however the same may not be happening for mobile web (MWeb) due to compatibility issues, different classes and ids used, leading to inconsistent tracking.

Best Practice: Design and test all triggers to work reliably across both desktop and mobile web environments. Always validate your tag firing behavior on mobile browser versions as well using GTM Preview mode before publishing to ensure consistent tracking and performance across devices.

10. Failing to test before and after publishing

Publishing changes in GTM without testing can lead to unexpected issues and disruptions on your site and may impact user behavior.

Best Practice: Always use GTM’s Preview Mode to test your changes before publishing. This allows you to validate that tags, triggers, and variables function as expected in a live environment, without actually deploying them. Previewing helps identify errors early, reducing the risk of flawed implementations going live.

 Preview mode

Conclusion:

By proactively addressing these common issues and applying the recommended best practices, you can significantly enhance the efficiency and reliability of your Google Tag Manager setup. This leads to more accurate and consistent data tracking across your website, reduces the risk of errors or data loss, and simplifies long-term tag management.

This is Part 1 of our GTM optimization series; stay tuned for Part 2, which will cover more effective and advanced troubleshooting solutions.

For more information, please contact AnalyticsLiv