mysqldump unknown option no beep

Same issue, commented out (#) the no-beep line in the MySQL my.ini, solved the problem.

I found this answer on dba.stackexchange.com, which is very helpful:

The no-beep option causes the mysql command line client not to beep when errors occur.

If that's an option you want, it should be in the [mysql] section of your my.cnf [or my.ini]. This error suggests that it's in the [client] section of your my.cnf, which causes [...] to throw the error since the option isn't recognized.

Check your my.cnf and either remove the line or place it in the [mysql] section instead of [client] and you should be good.

The [client] option group is read by all client programs (but not by mysqld). This enables you to specify options that apply to all clients. For example, [client] is the perfect group to use to specify the password that you use to connect to the server. (But make sure that the option file is readable and writable only by yourself, so that other people cannot find out your password.) Be sure not to put an option in the [client] group unless it is recognized by all client programs that you use. Programs that do not understand the option quit after displaying an error message if you try to run them.

-- http://dev.mysql.com/doc/refman/5.6/en/option-files.html

Something in an environment variable or my.cnf file?

For what it's worth, when I put the no-beep option (a valid option for the mysql client, but not for mysqldump) in the [client] section of my config file, I get

mysqldump: unknown option '--no-beep'

(As mentioned in naitsirch's answer, it should be moved from the [client] section to the [mysql] section so it doesn't try to use it for other client programs such as mysqldump.)