Sometimes Iguana cannot connect to MySQL on Windows, as it cannot find the native driver file (libmysql.dll).
This appears to be caused by a MySQL bug.
On Windows Iguana is unable to connect to MySQL because it cannot find the the libmysql.dll.
The solution is simple: Copy the libmysql.dll file from <MYSQLHOME>\lib to <MYSQLHOME>\bin.
Where MYSQLHOME is the MySQL home directory, something like:
“C:\Program Files\MySQL\MySQL Server 5.7”