Can anyone explain this error message?

[Harry Putnam <reader@newsguy.com>]

When I start gnus, or scan for news/mail

I get this error in echo area (wrapped for mail):

  Mail source (directory :path /home/reader/spool/in/ :suffix .in
  :predicate #[(file) \301\b!\302\230\207 [file file-name-nondirectory
  cron_tr.in] 2]) error (Searching for program).  Continue? (y or n) y

In gnus I have this:
(setq mail-sources
           '((file :path "/var/spool/mail/reader")
             (directory :path "/home/reader/spool/in/"    :suffix ".in")))

There are dozens of mbox style files in there, all ending in *.in
When scanned, gnus slurps them up and delivers to nnml groups of the
same name minus the `.in' part.

But for some reason the file mentioned in the error (cron_tr.in) has a
problem.

I don't see anything unusual about it, but did delete it.. Of course
it gets recreated when procmail delivers more msgs to it.  Just like
all the other *.in files...

Once again I hit the error after it gets recreated.

[Further note from a day later:  I see now after deleting all tine
*.in files that all are causing the same error with different
filename. of course.  All `searching for program'.

What program would that be... far as I know its gnus itself that does
the slurping, after procmail writes to those mbox style files.


I made no changes in .procmailrc .gnus or .emacs, however: I did
recreate the emacs directory created by git, from a backup of a few
hours earlier, due to problems with gnus failing to get mail from
several nnimap groups following a git pull and rebuild of emacs
yesterday (170725).

Something I've done with no problems a time or two in the past.

That is when the error started to appear.

Must have lost something that handles the transfer of of those mbox
files to nnml folders.