Recent versions of Perl (v5.24.1+) removed '.' from @INC, so this is probably right on the mark. If the OP is using a recent enough Perl version it will not look in the dot path unless something like this happens:

use lib '.';
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Though that is subject to the challenges that the dot path has always faced. It would be better to do something like this:

use FindBin;
use lib "$FindBin::Bin/../lib"; # Or whatever is accurate for this scr
+ipt's needs.
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This eliminates sensitivity to where the script was invoked from.

See also: FindBin, lib, and perl5241delta.

Based on this post by the OP it sounds like this is the problem!

Just to add a little info: Unfortunately the 5.24.1 doc is not up on http://perldoc.perl.org yet, so here is the link to the source. It seems that do's mechanism of searching @INC was impacted by this change - some interesting further reading for the curious is in the P5P threads The tricky issue of do() and [perl #131069] do file: Add './' in additional cases. Update: So as far as I understand it, the issue might be improved upon in v5.26 when that gets released.

At the start of your first-linked P5P thread, haukex:

Which means simply saying "welp, . isn't in @INC anymore" is going to leave a vast number of broken scripts, most of them likely the ones whose users are least knowledgable about perl (do 'config.pl' is very common baby perl, I think).

Fair comment!

I'm likely to solve it by automating a massive search-and-replace, inserting a './' before all filenames. (Might just back up first!). I think I know enough to know that the removal of '.' from @INC is best not over-ridden!

Many thanks to everyone who contributed to this. You are a wise and, yes, very attractive bunch of people!

Recent versions of Perl (v5.24.1+) removed '.' from @INC

I knew this is coming for 5.26.0+ ... but backporting it before 5.26.0 is released seems rather extraordinary to me.

For the OP's case, I think

do './test-response.pl';
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is sufficient.

Cheers,
Rob

Intriguing, though a bit technical for me to grasp. I update the OS religiously, and this might have been a trigger. Currently seem to be on Perl v5.24.1.

Recent versions of Perl (v5.24.1+) removed '.' from @INC,

Ehm , why?

Because something as seemingly safe as use strict can load strict.pm from the current working directory, which might be somewhere globally writable like "/tmp/".

There was apparently a real-world way of exploiting this to do nasty stuff, but the Perl development team haven't yet publicly disclosed what it is. I imagine it's an exploit in some commonly used Perl web app like cPanel or Webmin. They do plan on releasing the info eventually, once they've decided people have had enough time to move to newer Perl versions which don't have "." in @INC by default.

Here's one blog post that describes some background of the situation. Here's a blog post from Brian D. Foy talking about '.' being removed from @INC in 5.26.

Also, it's documented in the perldelta for 5.24.1.

And there's also a CVE for this issue too (CVE-2016-1238).