Even within franchises that are of literary origin, rather than cinematic, and even in those that have never had any officially licensed non-canonical content, there are contradictions.
Take Oz, for example. Even though the 1939 MGM movie has supplanted the original novels in popular culture (to the point where the writers of the 1985 Disney film,
Return to Oz, felt somehow compelled to make numerous nods to it, none of which made positive contributions to the story), it is the original 14 novels, not the movie, that is the canon source. In
The Wonderful Wizard of Oz, Glinda was described as the Good Witch of the South, but (evidently in response to objections from those who considered "good witch" to be oxymoronic) the 13 subsequent books referred to her as a
sorceress (and I believe the introduction to one of the books mentions that change in terminology specifically). And in
Wizard, it's stated that there were, at the time of Dorothy's arrival, but four witches in Oz, the Good Witches of the North and South, and the Wicked Witches of the East (killed when Dorothy's house landed on her) and West (melted down with a bucket of scrub water), but additional witches (e.g., Mombi and Blinkie), along with characters who were witches in everything but name, were introduced in the subsequent books. More pointedly, in
The Marvelous Land of Oz (the only canonical Oz book in which Dorothy doesn't appear), the Wizard is very specifically stated to have handed over the infant Ozma to the custody of the witch Mombi, and is vilified for having done so; in
Dorothy and the Wizard in Oz, however, all is forgiven, and Baum, having realized that he'd painted himself into a corner by vilifying the Wizard, conveniently forgot having ever done so. (Decades later, Hugh Pendexter III's non-canonical 1977 short story, "Oz and the Three Witches," manages a remarkable feat of retconning away the seeming contradiction; I'll only say that in Pendexter's version, the Wizard wasn't aware of the child's importance, but was very well aware that between Mombi and the Wicked Witches of the East and West, Mombi was the least of three evils, and the only one of the three who would have any compunctions about killing Ozma).
And take Alan Dean Foster's Humanx Commonwealth, a print-only, single-author-only, milieu since its 1972 inception. In 1977's Orphan Star (only the fifth HC book, and only the third Flinx book), we have this:
Body surfing was hardly an activity native to the thranx, but like many human sports, it had been adopted joyfully by them. They brought their own beauty to it. While a thranx in the water could never match the seal-like suppleness of a human, when it came to nakedly riding the waves they were far superior. Flinx saw their buoyant, hard-shelled bodies dancing at the forefront of successive waves, b-thorax pushed forward to permit air to reach breathing spicules.
Occasionally, a human would mount the back of a thranx friend for a double ride. It was no inconvenience to the insectoid mount, whose body was harder and nearly as buoyant as the elliptical boards themselves.
(Alan Dean Foster,
Orphan Star, New York: Ballantine, 1977, first edition, second printing, page 63)
Yet later HC novels completely contradicted this, describing the Thranx as being terrified (as an entire species) of immersion in water (quite understandable, given that they breathe through spicules on the b-thorax).
I still haven't seen SW7:TFA, but I can certainly understand how it would throw out vast amounts of literature that was, at best, deuterocanonical in nature.
Of course, being an ADF fan, I rather object to
Splinter being lumped together with such rubbish as the Han Solo and Lando Calrissian trilogies, and like it better than I like a lot of what's in the more recent SW EU continuity (and indeed, I've just about completely given up on SW lit, most of which I find to be boring, confusing, excessively violent, and far too liberally peppered with gratuitous "gross-out" scenes).
