I have create one class which implements Messaging.InboundEmailHandler
.
It was working fine until now, but now I am getting Invalid type: EmailMessage
while editing the class.
And, when testing the same I am getting FATAL_ERROR Internal Salesforce.com Error
EmailMessage
in your case). You need to search your code for where you did this, and change those identifier names (or if it's a class, delete and re-create it with a more carefully chosen name).