Thank you for your guide,

I managed to create a self contained example that reproduces the problem.

Now, I ran your test and it works on both perl versions, as you said.

But running the regex inside Expect.pm fails.

So the bug is in the expect package?

chain.txt

######################################################################
+########\r\n# This system is a restricted access system.             
+                  #\r\n# If collected security information reveals po
+ssible criminal activity that  #\r\n# exceeds privileges, evidence of
+ such activity may be provided to the rele- #\r\n# vantauthorities fo
+r further action. By continuing past this point, you #\r\n# expressly
+ consent to this security monitoring.              #\r\n#############
+#################################################################\r\n
+\r\nhostname: ~#
[download]

test.pl

use strict;
use Expect;

my $re1 = '(([#%:>~\$\] ])(?!\2)){3,4}|([\w\-\.]*)\$ *$|(\w[@\/]\w|sft
+p).*?[#%>~\$\]]|^[#%\$>\:]~] *$';
my $test;

open($test,"<","chain.txt");

my $exp = Expect->exp_init($test);

$exp->expect(1,
    [ $re1 => sub {
        my $exp = shift;
        print "Match before : ",$exp->before(),"\n";
        print "Match        : ",$exp->match(),"\n";
        print "Match after  : ",$exp->after(),"\n";
    }]
);

close $test;
[download]

---

hans@hans-desktop  ~  perl -v
This is perl 5, version 30, subversion 0 (v5.30.0) built for x86_64-li
+nux-gnu-thread-multi
hans@hans-desktop ~ perl -MExpect -e 'print $Expect::VERSION ."\n";'
1.21

perl test.pl
Match before : #######################################################
+#######################\r\n# This system is a restricted access syste
+m.                               #\r\n# If collected security informa
+tion reveals possible criminal activity that  #\r\n# exceeds privileg
+es, evidence of such activity may be provided to the rele- #\r\n# van
+tauthorities for further action. By continuing past this point, you #
+\r\n# expressly consent to this security monitoring.              #\r
+\n###################################################################
+###########\r\n\r\nhostname
Match        : : ~#
Match after  :
[download]

---

[hans@fedora ~]$ perl -v
This is perl 5, version 34, subversion 0 (v5.34.0) built for x86_64-li
+nux-thread-multi
[hans@fedora ~]$ perl -MExpect -e 'print $Expect::VERSION ."\n";'
1.35

[hans@fedora ~]$ perl test.pl 
Match before : #######################################################
+#######################\r\n# This system is a restricted access syste
+m.                             
Match        :   #
Match after  : \r\n# If collected security information reveals possibl
+e criminal activity that  #\r\n# exceeds privileges, evidence of such
+ activity may be provided to the rele- #\r\n# vantauthorities for fur
+ther action. By continuing past this point, you #\r\n# expressly cons
+ent to this security monitoring.              #\r\n##################
+############################################################\r\n\r\nh
+ostname: ~#
[download]

---

---

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