Steps to replicate:

1. On an existing page create a link to a new page One
2. Create page One with a link to page Two
3. Create page Two
4. Rename page One to OneRenamed (with update referrers selected)
5. Rename page Two to TwoRenamed (with update referrers selected)

Now you should get the error:

JSPWiki has detected an error

Error Message
    An unknown exception java.lang.NullPointerException was caught by Error.jsp.
Exception
    java.lang.NullPointerException
Place where detected
    com.ecyrd.jspwiki.PageManager.getCurrentLock(), line 314

If you have changed the templates, please do check them. This error message may show up because of that. If you have not changed them, and you are either installing JSPWiki for the first time or have changed configuration, then you might want to check your configuration files. If you are absolutely sure that JSPWiki was running quite okay or you can't figure out what is going on, then by all means, come over to jspwiki.org and tell us. There is more information in the log file (like the full stack trace, which you should add to any error report).

And don't worry - it's just a computer program. Nothing really serious is probably going on: at worst you can lose a few nights sleep. It's not like it's the end of the world.

After this page Two has been renamed to TwoRenamed. However, the link on page OneRenamed has not been updated to TwoRenamed and points to the now non-existing page Two.

I have seen this happening in our environment too, several times, but didn't have the time yet to determine the exact circumstances. We also run 2.4.87.

--HarryMetske, 15-Jan-2007

Happens also with v2.4.100. I wasn't able to figure out a pattern.

--AnonymousCoward, 15-Mar-2007

--HarryMetske