What is lambda
?
lambda_*
functions are the (newer) equivalent to anonymous functions in PHP. They’re pretty comparable to how you define functions on the fly in Javascript.
Why does that happen?
When you see such an output, then it normally means, that at some point – in some codepiece – there’s a function not only (silently) returning something, but echo/print
-ing something. When lambda_*
is actually the output printed to the screen, then I’d say, it’s a function defined inside another function that is returning something by accident.
Debugging and Backtracing
As it happens on the login screen, I’d suggest to take a look at the wp-login.php
file, search for all do_action
and apply_filters
appearances. Write them down and then do a cross file search in your plugins and/or theme and check if you got a callback somewhere attached to one of those hooks or filters. Now go and check all of those and take a look if one of those functions has either a lambda function
inside or calls to other (non-core) functions, that have such a call.
When you’re done and have found all those lambda functions, then inspect which one of them echo
s or print
s something. If you’re still left with more than one, then there’s a high chance that you can determine the error prone function using your brain and read its name, or just dig into it and kill the echo/print
one by one (and reload the login page on each try) until you’ve found the function causing it.
What to do now?
That’s pretty easy: Contact the author with a detailed problem & error description and with steps that show how you fixed the bug.