Site administration>Reports>Spam cleaner.

Steps taken
Enter a set of keywords and click on search
Or Click on Autodetect spam

ERROR
ERROR: Incorrect number of query parameters. Expected x, got 0.
Where x is the number of keywords you typed plus one

Stack trace:

• line 697 of \lib\dml\moodle_database.php: dml_exception thrown
• line 743 of \lib\dml\mysqli_native_moodle_database.php: call to moodle_database->fix_sql_params()
• line 165 of \admin\report\spamcleaner\index.php: call to mysqli_native_moodle_database->get_recordset_sql()
• line 129 of \admin\report\spamcleaner\index.php: call to search_spammers()

First look comments
Clearly get_recordset_sql() is missing second set of arguments