If you update your BCS Model, you may need to restart the OSearch14 service

I'm experimenting with the SharePoint 2010 BCS at the moment, using custom .net code to implement the IdEnumerator and SpecificFinder methods, to be used in the Search Crawler.

As this is backed by a .net class, I had some issues getting changes to it done. I've added a new field, updated the .bdcm file, redeployed and started a Full Crawl, only to get error messages in the Crawl saying that the Property that I've added cannot be found in the backing class.

Solution is as simple as logical: Reset the SharePoint Server Search 14 service (OSearch14). As this holds the Assembly in memory and as the Sharepoint deployment tools do only recycle the IIS process, there will be a mismatch between the .bdcm file and the (outdated, but still loaded) assembly.

Also, you might have to re-create the Content Source. And don't forget to increase the version number if you edit the .bdcm file manually.