Solr 3.1 to 3.6 upgrade syntax changes

Question

Tried to upgrade and application from Solr 3.1 to 3.6.1 and stumbled upon the following issue: The query like the one shown below worked in 3.1 but does not return any results in 3.6.1:

q=id:911 AND (format:text OR format:null)

defType is set to edismax and q.op set to AND.

Could someone please point me to the point in release notes or SOLR documentation that explains when and why the change was introduced.

Answer 1

Found the reason. Just did not believe it could be a bug. That simple.