Specifically that the 'harvest source' needs to have the gemini 2.3 configuration in the harvest settings. In the bottom "Configuration" text field Gemini 2.3 harvests have the following json:
Note: even with this, sometimes data.gov.uk decides to harvest my CSW as if it is providing GEMINI 2.2 files and therefore raise errors against all of them.
Specifically that the 'harvest source' needs to have the gemini 2.3 configuration in the harvest settings. In the bottom "Configuration" text field Gemini 2.3 harvests have the following json:
{"validator_profiles": ["iso19139eden", "constraints-1.4", "gemini2-3"]}