Under certain circumstances
* a taxonomy term reference field is not displayed
* Watchdog shows the Notice: Undefined index: taxonomy_term in taxonomy_field_formatter_view() (line 1596 of taxonomy.module)
Analysis
It looks that in taxonomy_field_formatter_view() under certain circumstances $item['tid'] is set, but not $item['taxonomy_term'].
Original summary
There are several people reporting this issue in other projects:
- https://drupal.org/node/2020117
- #1970540: Notice: Undefined index: taxonomy_term in taxonomy_field_formatter_view() (line 1610 of
- #1978082: Error when preview: Notice: Undefined index: taxonomy_term in taxonomy_field_formatter_view
The site I'm experiencing the error on doesn't run any contrib taxonomy modules, so it seems like a core issue.
I do run Display Suite on the site, but disabling it has no effect on the error.
I've created a patch that resolves the error on my site. I'll attach after creating this issue.