In my tests, which use Selenium client driver API, calling Selenium#retrieveLastRemoteControlLogs() results in "com.thoughtworks.selenium.SeleniumException: Internal Server Error". This is because Selenium server (Jetty) returns HTTP response code 500 after invoking HttpCommandProcessor#getCommandResponseAsString("cmd=retrieveLastRemoteControlLogs"). In fact, each server response with code other than 200 (OK) raises a SeleniumException with non-descriptive generic message built from the response code, for example "Internal Server Error". I would personally prefer something more sensible, e.g. "error while processing command ABC, server returned code XYZ". Anyway, this means that the error occurs on Selenium server (servlet bound to "/selenium-server/driver/" throws an exception). Root cause for this exception is in SeleniumDriverResourceHandler#doCommand(...) method, line 558: ... } else if (RetrieveLastRemoteControlLogsCommand.ID.equals(cmd)) { /* Trim logs to avoid Larsen effect (see remote control stability tests) */ LOGGER.info("Got result:" + results.substring(0, 30) + "... on session " + sessionId); } ... If result.length() >= 30, this will throw "java.lang.StringIndexOutOfBoundsException: String index out of range: 30". Proposed fix: don't call results.substring(0, 30) unless you know its length is less than 30 characters.