Unsupported operand types

I'm getting the same error when I try to send an e-mail using advuser.

This error is because a module, a theme or a block of code you entered is calling url() using the old params... and it's not a very robust url() function so it dies :)

Here's a writeup on the problem, and what I did to solve it

Any idea why this error occurs when cron.php runs on a cron schedule, but not when I run it manually?

BTW, in my case, Flickr-Sync isn't the cause, I don't have this module installed.

I was unable to reproduce this issue. Since this is an old issue, i'm going to close the issue but feel free to open if you've encountered this issue.