can you show the code? and the response?

Yes, of course, but I've just changed:

$m->max_redirect(2);

to:

$m->max_redirect(0);

On a closer look, the result is not entirely the same but also not much better (redirect loop detected):

Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Date: Fri, 22 Nov 2019 22:25:09 GMT
Pragma: no-cache
Via: url
Server: servername
Vary: Accept-Encoding,Origin
Content-Encoding: gzip
Content-Language: en
Content-Length: 6336
Content-Type: text/html;charset=UTF-8
Expires: 0
Client-Date: Fri, 22 Nov 2019 22:29:13 GMT
Client-Peer: xxx.xxx.xxx.xxx:443
Client-Response-Num: 1
Client-SSL-Cert-Issuer: /certinfo
Client-SSL-Cert-Subject: /certinfo
Client-SSL-Cipher: ECDHE-RSA-AES256-GCM-SHA384
Client-SSL-Socket-Class: IO::Socket::SSL
Client-SSL-Warning: Peer certificate not verified
Client-Warning: Redirect loop detected (max_redirect = 0)
Strict-Transport-Security: max-age=15768000 ; includeSubDomains
Strict-Transport-Security: max-age=15768000
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
X-XSS-Protection: 1; mode=block
[download]

Strange, isn't it?

Change that user-agent string to something valid instead of myagent.

When I hit facebook with that script I get a Location header item as expected.

Regarding autocheck=>1, from WWW::Mechanize manpage:

Checks each request made to see if it was successful. This saves you t
+he trouble of manually checking yourself. Any errors found are errors
+, not warnings.
[download]

Setting max_redirect=0 is good for making sure things work and gives you all control. But there is an easier way to do it:

$m->max_redirect(3); # whatever redirects you may thing you will get o
+r more
my $content = $m->post($uri);

my $ri=0;
foreach my $aredirect ($content->redirects()){
        $ri++;
        print "REDIRECT $ri ******\n".($aredirect->as_string())."\nEND
+ ****\n\n";  
}
[download]

That is, you loop through the headers of each of the redirects encountered to get what you need and at the same time you are at your final URL to hit login.

bw, bliako