Why does this code generate the error “The end tag ”</c:when“ is unbalanced”?

Question

I don\'t understand why I get the error:

The end tag \"

when this code is run:

Answer 1

For me, I forgot to close a JSTL tag.

This is where should I fix

And after I changed to this it's fine.

or

Some tricks to fix this problem quickly: If you have IDEs like Netbeans, please try 1.Collapse all tags and expand one by one to see which one you did not close. 2. Type " and look at the popup menu(if you have enabled it). If there is any unclosed tag it will show up.