Latest newtx package update (v1.601 Oct 2, 2019) breaks the footnote command [update: bug fixed by package author]

It is quite normal that the enc file is located in the dvips sub-tree. The problem here is that the map file requests ntxsups_T1.enc but the actual file is called ntxsups_t1.enc. This is no problem on case-insensitive file systems. As a work-around I would try (untested):

$ mkdir -p ~/texmf/fonts/enc/dvips/newtx
$ cp /usr/local/texlive/2019/texmf-dist/fonts/enc/dvips/newtx/ntxsups_t1.enc \
    ~/texmf/fonts/enc/dvips/newtx/ntxsups_T1.enc

The newtx distribution provides the file newtx.map for rebuilding the main map files (mainly pdftex.map). In this file we read

ntxsups-Regular-ot1 ntxsups-Regular " ntxsupsOT1Encoding ReEncodeFont " <[ntxsups_OT1.enc <ntxsups-Regular.pfb
ntxsups-Regular-t1 ntxsups-Regular " ntxsupsT1Encoding ReEncodeFont " <[ntxsups_T1.enc <ntxsups-Regular.pfb
ntxsups-Regular-ly1 ntxsups-Regular " ntxsupsLY1Encoding ReEncodeFont " <[ntxsups_LY1.enc <ntxsups-Regular.pfb
ntxsups-Italic-ot1 ntxsups-Italic " ntxsupsOT1Encoding ReEncodeFont " <[ntxsups_OT1.enc <ntxsups-Italic.pfb
ntxsups-Italic-t1 ntxsups-Italic " ntxsupsT1Encoding ReEncodeFont " <[ntxsups_T1.enc <ntxsups-Italic.pfb
ntxsups-Italic-ly1 ntxsups-Italic " ntxsupsLY1Encoding ReEncodeFont " <[ntxsups_LY1.enc <ntxsups-Italic.pfb
ntxsups-Bold-ot1 ntxsups-Bold " ntxsupsOT1Encoding ReEncodeFont " <[ntxsups_OT1.enc <ntxsups-Bold.pfb
ntxsups-Bold-t1 ntxsups-Bold " ntxsupsT1Encoding ReEncodeFont " <[ntxsups_T1.enc <ntxsups-Bold.pfb
ntxsups-Bold-ly1 ntxsups-Bold " ntxsupsLY1Encoding ReEncodeFont " <[ntxsups_LY1.enc <ntxsups-Bold.pfb
ntxsups-BoldItalic-ot1 ntxsups-BoldItalic " ntxsupsOT1Encoding ReEncodeFont " <[ntxsups_OT1.enc <ntxsups-BoldItalic.pfb
ntxsups-BoldItalic-t1 ntxsups-BoldItalic " ntxsupsT1Encoding ReEncodeFont " <[ntxsups_T1.enc <ntxsups-BoldItalic.pfb
ntxsups-BoldItalic-ly1 ntxsups-BoldItalic " ntxsupsLY1Encoding ReEncodeFont " <ntxsups_LY1.enc <ntxsups-BoldItalic.pfb

but the corresponding files are named

ntxsups_ot1.enc
ntxsups_t1.enc
ntxsups_ly1.enc

The newtx.map file should be fixed to contain the correct names. The problem doesn't show up on Windows systems, that are case insensitive.

With suitable privileges open

/usr/local/texlive/2019/texmf-dist/fonts/map/dvips/newtx/newtx.map

Fix the faulty entries shown above changing the file names to match the distributed ones, save and, again with suitable privileges, run

updmap -sys

Once the package is updated, the fix will disappear, whatever method the package maintainer will choose to use in order to correct the faulty behavior.

The fix has been tested.