Error: Translation helpers module not found.

I don't know anything beyond that error message, sorry.

I've seen code in Flag that implies that there is functionality that flags across translations, so if I flag the English version of a node, then the node that is the Swedish translation of that node is also considered as flagged. The project page for Translation helpers module seems to suggest that's what it's needed to.

Have you had a look in the Flag documentation pages, or the README? Is there anything further there?

If not, I suggest you have a look in the Flag code and see if you see any of Translation helpers module's hooks implemented. If you manage to figure anything out, do please share that here, and maybe consider creating a docs page on that if there isn't one already.

It's only in flag_node_translation_change() where we use it. Maybe it should be a warning rather than an error... I don't see any dire consequences for having it turned off.

I agree that this error should be suppressed - changing it to warning instead also seems like a bad idea. If you want to give site builders/developers an opportunity to understand and use cross-translated-content flagging (like explained in #1), then I suggest you just provide the right information in Readme file :)

On any multilingual site that im running with flag module that doesn't use node translation, everything works fine but status page shows this error which is annoying since it prints all over the admin pages and we (developers) have to patch flag module to not show it.

Take a look how views is showing the message about "Advanced help" module integration. The message is there on admin/structure/views, but it can be turned off in views -> settings (which I always do by the way :)).

Cheers :)

we (developers) have to patch flag module to not show it.

Where's your patch then?

It looks like conditions to display this requirements "error" are simply flag + translation installed with translation_helpers not installed. So anyone without a multilingual site, or with a multilingual site using entity_translation instead of translation, won't see the message (good). Anyone using translations who also has flags on entity types configured with translations will see this message (also good, since they probably need to know about this). All that leaves are those who are using translation but not on entity types that also use flags. For this latter group, which I suppose is probably a minority, showing this message as an error is certainly confusing, but having a message of some sort appear is probably not a big issue (IMHO). How about we just reduce it to a warning (as in the patch)?

If the consensus is instead to drop the message completely, I'm also happy to roll a patch for that... mostly I just agree that this does not justify an error-level message.

Sounds fair!

Changing the status message from error to warning is indeed the best option. Still shows enough priority to investigate the message.

Thanks everyone for working on this. Committed.