I kept getting this error on my page. After a little bit of reading it seems to be a bug with JDeveloper. Something about a naming bug with the page def.
The easy fix. Backup what you have then delete your form components in the Structure and then just re-drag them onto the page.
What this means:Your jsp/jspx file has grown too big.
Fix:Do a JSP include.
It helps split the file up and yet to the browser the page still looks like it is one file.
Here is what the include looks like:
<%@ include file=”/includes/NewFile.jspf”%>
There is a trick where you can get ADF not to create a Page Def file for NewFile’s but rather point to point to the first one. I never figured that out. What I did was let ADF create the NewFile’s page def and just mirror it from the old file. I know, this is really bad but it had to be done at the time.