If application have multiple classloader ,like Websphere.
There is a chance that one classloader which load LoggerConext and another load logback.xml. This incident lead to "can NOT find [logback.xml]" message.

Reproduce problem :
1.Using spring scheduler which is launched before web sevlets start-> this will produce 2 classloader in single application.

2. Using shared library which have slf4j & logback jar file.

after launch , the first classloader is set classpath to shared library . The second one is load class from web's WEB-INF/class which have logback.xml

After using StatusPrinter.print(lc);
logback will print "can NOT find [logback.xml]".

interim solution for me:
solution 1: copy logback.xml into shared library
solution 2: change classloader behaviour to single classloader per application.

Attached file for more info.