Fix Looker Studio error: Undefined ‘endDate’ property

What is the error: Cannot read property of undefined (readin 'endDate').

In Looker Studio, all data sources with historicized data have a date field of reference.

Looker Studio uses this to filter your data by date without you telling him how to. But sometimes, you'll find your report full of errors, and the details give you this :

"Cannot read property of undefined (readin 'endDate')."

It is the way for Looker Studio to let you know that the date fields of reference have been lost.

Your data source is, therefore, only usable once fixed.

How to identify this issue?

In addition to the error message, one significant difference is visible in your report: in the configuration column of each chart, Looker Studio now asks for a date field just under the data source :

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How to solve it?

The best way to solve this is to deactivate and then reactivate the edition of the field for editors.

To do so:

• Open the data source by going to Resource -> Manage Added Data Source.
• Click the Edit button on the good row.
• Locate the Field editing in reports at the top right and click on it.
• Close the overlay and refresh your report. At this point, your data should start to come back.
• Reactivate the Field edition in reports by following the same steps.

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Note: 

• Sometimes the data doesn't come back the first time of trying. You can reactivate and deactivate the field edition in reports one more time.
• Sometimes reactivating the field edition in reports make the error appears again. You can leave it off. It only prevents report editors from modifying the fields in the data source.

If it still not works, the best way to retrieve your report quickly is to duplicate your broken data source. 

The new copy will not have this issue, and you can update the data source in your report charts easily :

• Right-click on a component, then Select, Select Charts with the same data source on Page
• In the configuration column, you can now mass edit the data source of your component.

If you duplicate the previous data sources, all your calculated fields are also copied. When you change the data source, Looker Studio will find it automatically, and you won't have to do your report again!