I presume that the login processing URL is the filterProcessesUrl on my custom AuthenticationProcessingFilter:
<property name="filterProcessesUrl" value="/j_security_check"/>
Someone else may know more about what <form-login login-processing-url="/path"> actually does.
I have no idea what form-login does but when I replaced "j_security_check" with "processLogin" it got passed my previous error. I'm not sure if this will cause a negative effect later.
Can someone help clear up what form-login is doing and how replacing it should be configured?
form-login creates an AuthenticationProcessingFilter. This is explained here
You need to understand how this and the other filters work if you are going to customize them. The property "filterProcessesUrl" aka "login-processing-url" defaults to "/j_spring_security_check" and is the URL that the login form should submit to and which the filter will intercept to handle the login request. Using "/j_security_check" is not a good idea as that is the default J2EE form login URL and some containers may choose to process it themselves without presenting it to the application.