You must download several jar files before you can build Middlegen. Execute the "download-deps" target. Then try to build again. If you are behind a proxy, you should define the properties http.proxyHost and http.proxyPort. Example: ant -Dhttp.proxyHost=foo.com -Dhttp.proxyPort=8080 It's also possible to download the jars manually. The JDBC driver you have specified by including one of the files in ${basedir}/config/database doesn't exist. You have to download this driver separately and put it in ${database.driver.file} Please make sure you're using a version that is equal or superior to the one we looked for. If you name the driver jar file differently, please update the database.driver.file property in the ${basedir}/config/database/xxx.xml file accordingly.