When iam attempeting to updates version 14.6 it failed why?

If you're trying to update your device wirelessly (via wifi), read this support article:--> If your iPhone, iPad or iPod touch won’t update.

As an alternative , you can update your iPhone connecting it to a computer running iTunes (Windows PC), or iTunes/Finder (Mac).

If the issue still persists, contact Apple Support directly, using this link:--> Get Support

Regards

Giulio