You are confused. There is no such thing as "Lightroom 6" or "LR6 software (5.6)".
The latest release of Lightroom is Lr 5, and its latest update is Lr 5.6.
The 8.6 version of the ACR plug-in is irrelevant to Lightroom. Lightroom uses its own conversion engine, which works similar to Adobe Camera Raw, but Lightroom does not use the ACR plug-in at all. That plug-in is for Photoshop only.
As such, your question belongs in the Lightroom forum, not here.
The error message in your screen shot seems to refer to two corrupted image files which cannot be read.
Not sure whether that camera model is a Nikon or a Canon model. Had perhaps any Canon or Nikon software been used in any shape or form on those files, even to transfer them to your machine? As an example, some versions of the Nikon software are known to damage files.