You are seeing this particular error for one of the following reasons, starting with the most common reason:
- There really are no page template sets defined anywhere in the sytem. Add some.
- For some reason the TypoScript is not being recognised. Check your templates - using the Template Analyser if necessary. It might be a syntax problem, a typo or similar.
- Configuration does exist but consists of empty values - which can happen if the template collection uses TypoScript constants but these have not been filled or miss default values.
- The PageConfigurationProvider from EXT:fluidpages has been overridden, replaced, modified or made incompatible in some way.