It seems that utf8x is not supported, or needed, on updated TL. From
David Carlisle:
utf8x by default does nothing now, but as a compromise
compatibility for some specific existing documents if you
explicitly load ucs then it and utf8x work as before, but that
over writes all of latex's default unicode handling and things
will go wrong. There really isn't much that can be said other than
don't load the package. The alternative would be to make ucs do
nothing as well, but that would stop some documents working that
currently work.
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