Hi @Reim Mahmoud ,
You’re correct that skillsets are optional. This issue maybe occurring because an indexer cache was accidentally added to your indexer’s definition. Indexer caches are a part of the indexer that can only be used with skillsets. Is there a way to remove the indexer cache from your indexer?
Enable caching for incremental enrichment (preview) - Azure Cognitive Search | Microsoft Learn
Also, can you let us know if you're indeed using 'import data', and what options you chose, so we can try to repro this issue on our end?
Thanks,
Grace