On older posts within the community, you may receive a translation error,

The error occurs because the author value is null in one of the posts within the topic. The author value is null as a result of migrating from Jive to Lithium.
Clicking the original error message will display the translation menu seen above to allow for the post to be translated to the language of choice.
There is no other workaround as the author of a post cannot be modified.