On Wed, 27 Sep 2017, Rich Shepard wrote:
I think I know why these issues have appeared this week when all previous letters (and documents using the other KOMA-Script classes) worked as expected: over the weekend I upgraded TeXLive from 2015 to 2017. There are likely changes in there that are incompatible with the settings I used to use. Possible?
I just checked by loading letters from 2011 and 2013. In both cases when I tried to display them error messages were presented. In one case, it did not like the ERT of \newpage. Told me it was undefined. Rich