Sessions decreased since June 9th


We noticed a decrease in sessions since June 9th, while nothing was changed in Piwik PRO over this period. No change in the way Piwik PRO is installed too.

We observe this decrease on the Google Ads traffic, while the Google Ads clicks were quite constant and even went up since June 9th.

There is always a difference between both tools, and we can usually explain it as clicks are different from sessions. But there seems to be an issue since June 9th. We checked the tracking template and the landing pages in Google Ads, and it’s all good.

In comparison, here are the stats from both tools from May 27th to June 8th:

Google Ads

Piwik PRO

As you can see, the charts are quite aligned.

Total differences for both periods:

  • May 27th - June 8th: 22,6K clicks for Google Ads, 20,9K sessions for Piwik PRO = 8% gap

  • June 9th - June 11th: 5,4K clicks for Google Ads, 3,4K sessions for Piwik PRO = 37% gap

I see changes were made to the tracker on June 4th: Version 18 - Changelog Piwik PRO.

“We fixed an issue where sessions were split when events had both campaign and referrer parameters, and the campaign parameter was later missing during the session.”

Could this explain the decrease? I’ll share the instance in private if needed.

Thank you!

Update: we are observing this on multiple instances and all traffic sources are impacted.

Hi. Our team is looking into that.

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We confirm that there’s an issue with processing the data which affects Core instances that started on the 10th of June. I’ll let you know once the issue is fixed. From that point in time it’ll take a while to reprocess the data for the whole affected period.

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Thank you Kuba! Great to know that you’ll be able to reprocess the data. :slight_smile:

Are you sure only Core instances are affected?

If there’s ano other instance that might be affected, please send me the URL via private message.

The issue has been resolved for the data collected from now on. I’ll post an update here once the historical data has been reprocessed.