'TYPO3 frontend-page shows section names

I have trouble with my frontend TYPO3 Site, because it shows the names of the sections. I don't know how to remove this alerts...
Thanks for help.

UPDATE:
I had changed the ERROR outputs from true to false. Clearing the Caches didn't affect anything, so I deleted all temp files and now it works.

Solution 1:^[1]

Since TYPO3 8.5 there is an option in the admin-panel to enable FLUID debug output (Release notes)

In the settings of the admin panel you find a checkbox for Show fluid debug output. just uncheck to disable all that output.

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Solution	Source
Solution 1	Bernd Wilke Ï€Ï†