It appears (to me) that you are setting "q" to equal q, rows, score, highlight, json, and phrasehighlighter. If these are all supposed to have their own name for each value, the string needs to be reformatted. There is also no closing ' for the string (not critical, but I consider it good form to always use a closing string delimiter.)
Also, you can do without the hashmarks, since the values are not contained within "double quotes".
<cfset theUrl = 'http://localhost:8090/solr/ktimatologio/select/?hl.requireFieldMatch=true&hl.fl=*&q=' & Arguments.q & '&rows=' & ARGUMENTS.rows & '&score=' & ARGUMENTS.score & '&highlight=' & ARGUMENTS.highlight & '&json=' & ARGUMENTS.json & '&phrasehighlighter=' & ARGUMENTS.phrasehighlighter & ''>