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How to remove February 2021 spam data from Google Analytics

Did you see a spike in your February 2021 website traffic? James Akers, Tech Champion for Data Analytics and Insight, explains what caused it, why it’s a problem and how you can filter it out of your reports.

What is the problem?

A large-scale automated bot attack sent fake Google Analytics traffic to non-existent web pages between 31st January and 1st February 2021. If your account was affected you’ll see a spike in users visiting pages such as:

  • /
  • /
  • /
  • /

These are not real pages on your website and they’re not real users. This spam data will affect metrics across your different reports in Google Analytics.

This attack was able to bypass the Bot Filtering setting to Exclude all hits from known bots and spiders  you may already have turned on in your account.

Google Analytics report with spike on 1 February 2021

A Google Analytics report showing 2,004 Pageviews to /

When we use a Secondary dimension for Browser Size we can see that this traffic has no data (not set). We can use this to isolate and exclude the data.

Google Analytics report with Browser Size Secondary dimension

Isolating the spam traffic using a Secondary dimension for Browser Size


How can I fix it?

Unfortunately there is no way to remove unwanted historical data in Google Analytics aggregated reports. Hopefully Google will be able to remove this from all affected accounts in time, but there’s yet to be an official confirmation of any intended fix. Until then, there are steps you can take to filter out this spam traffic from your account.

The spam traffic can be identified by looking for any sessions with Browser Size equals (not set). This article from Organic Digital details the discovery and identification of the issue and potential fixes.

You may wish to also exclude any Page Title equals (not set) if Browser Size does not exclude all spam traffic from your reports. Depending on the configuration of your site you may have pages which don’t have Page Titles (for example in a checkout process) so double check you’re not accidentally excluding real users.

Use Google Analytics Segments to exclude the data

When reviewing data that includes 31st January to 1st February 2021 use a Segment with the settings of Browser Size exactly matches (not set) . This will filter out any spam traffic in your specified date range.

Google Analytics segment settings for Browser Size

Google Analytics Segment settings to exclude spam with Browser Size (not set)

If you’re new to Segments in Google Analytics, check out this video tutorial from Benjamin at Loves Data.

Filter out the traffic in your data visualisation tool

If you’re using a visualsation tool Google Data Studio or Power BI you can apply a filter to all charts to remove the spam traffic.

Example Google Data Studio filter settings

Example Google Data Studio filter settings


Add a Google Analytics filter to block future attacks

A Filter added to your Google Analytics View can stop spam traffic of this type ever reaching your account. Create a custom Filter which excludes traffic where the Browser Size matches (not set).

Warning! Filters change the core data in you account View. When adding any new Filters it’s recommended to add them to a test View first to ensure it’s configured correctly and doesn’t affect any other data.

Google Analytics filter set up

Google Analytics filter settings to prevent future attacks

Filters do not affect historical data so although no future traffic will appear, the spam data from 1st February will remain.

Need help?

The Digital Culture Network is here to support you and your organisation. Our Tech Champions can provide free 1-2-1 support to all arts and cultural organisations who are in receipt of, or eligible for, Arts Council England funding. If you need help or would like to chat with us about any of the advice we have covered above, please get in touch. Sign up for our newsletter below and follow us on Twitter @ace_dcn for the latest updates.

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