If your scheduled report arrives by email with some pages showing "Unknown data source" where the charts should be, but the same report looks perfect when you open it yourself, your data is fine. The report is running out of time while Google builds the PDF in the background. This article shows you how to confirm that and how to make the scheduled version reliable.

Confirm it is this and not something else

1. Open the report in your browser and go to the page that came through blank.
2. Check that the charts render normally. If they do, your connection and your data are working.
3. Download the report manually using Share > Download report.
4. Compare that PDF to the emailed one. If the manual download is complete and the emailed one is not, this article applies.

Make the scheduled report reliable

The fastest fix is to make the report smaller. The permanent fix is to stop the scheduled report from waiting on a live connection at all.

1. Shorten the report's date range, or split a long report into two shorter scheduled reports.
2. If that is not enough, move the report onto a Google Sheet: build what you need in Data Builder, send it to Google Sheets, then point your Data Studio report at that Sheet.
3. Reschedule the delivery and confirm the next PDF arrives complete.

A Sheets-backed report reads from a spreadsheet instead of fetching live from each platform, so there is nothing for the scheduled render to wait on. This is the route worth setting up once for a report you need every month.

Why the emailed version fails when the live one works

When you open a report yourself, you wait while each page loads, however long that takes. When Google builds a scheduled PDF it does not wait: each page gets a fixed window to return its data, and any page that misses the window is written into the PDF as "Unknown data source" rather than retried.

That is why the failure moves around. A page that made it last month may miss this month simply because it was slower that day.

Why the same pages do not always fail

Nothing is broken on the pages that fail; they are just the slowest ones on the day. A report is more likely to hit this when it has many pages, many different platforms connected on one report, or a long date range, since all three make individual pages slower to build.

Is this the same as "Unknown data source" in a new template?

No, and this one trips people up. When you first copy one of our multi-source report templates, the data sources show as "unknown" until you connect your own accounts. That is a setup step, and it happens in the editor.

This article covers something different: a report that is already connected and working, where the words appear only in the delivered PDF. If you see "unknown" while setting up a fresh template, connect your accounts instead.

This affects only scheduled email delivery. Your live report, and any PDF you download yourself, are unaffected. On a Custom plan with data exports, you can route through BigQuery or a PMA-hosted database instead, which removes the time limit entirely; ask us if that fits your setup.

Troubleshooting

• Every page is blank, not just some. That is a different problem, usually a disconnected account. Open the report and check for a connection error.
• The manual download is also incomplete. Then this is not a scheduling issue. Shorten the date range and contact us with the report link.
• I moved to a Sheet and the data is stale. Check the refresh schedule on the Sheet itself. The report is only as fresh as the spreadsheet behind it.
• It came back after a few good months. Expected. The report likely grew. Check whether pages or data sources were added since it last worked.

Still need help?

Submit a ticket and include a link to the report plus the emailed PDF, so we can see the contrast between the two.

Related article: Community Connector Error: The data source API took longer than the 60 second Google Sheets or Data Studio timeout.