An important information was published with one of the individual July 2015 KB articles for SP2013 (KB 3054926) – and therefore potentially very good hidden: July 2015 CU for SharePoint 2013 changes the database schema for the analytics reporting database. The change was required to support URLs with up to 4000 characters length.
The caveat with this is that the crawler now expects the database schema to be updated and will fail to crawl if SharePoint Configuration Wizard did not run to update the database schema.
With other words: unlike other CUs it is mandatory to run the SharePoint Configuration Wizard right after installing the July 2015 CU binaries to ensure that crawl works correct.
If you are using PSCONFIG.EXE it is recommended to use the following commands:
PSConfig.exe -cmd upgrade -inplace b2b -wait -cmd applicationcontent -install -cmd installfeatures -cmd secureresources -cmd services -install