Error 500: Error processing GroovyPageView: null

I'm building a Grails/Groovy/GSP app.

I'm used to seeing errors such as "Cannot get property 'id' on null object", or "no property named ...". But I'm not sure what "null" by itself means!

Error 500: Error processing GroovyPageView: null

Just "null".

Now I understand that the full error stack is going to help, and I'm still studying it to understand the error. But I just wonder in general what type of error is just "null".

One other thing I noticed is that for error messages regarding groovy/gsp pages, the line numbers are always completely off and useless.

org.codehaus.groovy.grails.web.pages.exceptions.GroovyPagesException: Error processing GroovyPageView: null

    at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:199)

    at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:282)

    at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:754)

    at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:684)

    at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:876)

    at java.lang.Thread.run(Thread.开发者_如何学Cjava:619)

Caused by: java.lang.NullPointerException

    at gsp_shop_viewCategoryshow_gsp$_run_closure1.doCall(gsp_shop_viewCategoryshow_gsp.groovy:36)

    at gsp_shop_viewCategoryshow_gsp$_run_closure1.doCall(gsp_shop_viewCategoryshow_gsp.groovy)

    at gsp_shop_viewCategoryshow_gsp.run(gsp_shop_viewCategoryshow_gsp.groovy:54)

    ... 6 more

I'd again assume you are doing something with a null object in your gsp. If you don't see such a thing, go and fine gsp_shop_viewCategoryshow_gsp.groovy, and see what's there on line 36.

I'm not sure exactly where this file would reside, and it depends on the settings, but check your HOME/.grails folder.