Antes, o tomcat funcionava perfeitamente, fiz algumas aprimoramentos no meu programa e instalei o MySQL e começou a aparecer esse erro.
Pesquisando na net, eu vi indicando para deletar a pasta workspace/.metadata/.plugins/org.eclipse.core.resources ; não deu certo
Em outra pediram isso:
The solution was straightforward:
In Eclipse, open the Servers tab
Double-click on "Tomcat v7.0 Server at localhost"
The settings tab opens, click on the Open launch configuration link in General Information
The Edit Configuration screen opens, click on the Classpath tab.
Click on the “Add External JARs…” button and browse for the missing library. In my case it was the following:
Caused by: java.lang.IllegalArgumentException: The servlets named [br.com.leandro.bo.LoginBO] and [br.com.leandro.servlet.LoginServlet] are both mapped to the url-pattern [/login] which is not permitted