This message is generated when autoloading of the indicated file returns an expression that does not match the expected list of symbols.
This error should occur only if the files that set up the default autoloading system have been modified or damaged. For example, this error can occur if those files are not all from the same version of the Wolfram System.
Off[message] switches off the message; On[message] switches it on. For example: Off[General::badsys1].