Notice: Undefined index: tid in taxonomy_field_formatter_prepare_view() (line 1669 of I'm getting this error on my website. I have tried cleaning up the content type of all fields but it still shows up.

Any ideas what could be causing it, and how to debug?

Thanks a lot,

Chiko
Your content have an taxonomy_term reference field which have invaild data, maybe it break.

You can install devel module and use error display with debug_backtrace and you will see where it comming.