KnowledgeBase   →   "Internal apreq error" in Apache 2 httpd error logs

The error is triggered by the final line in the following code:

use Apache2::Request;
use Apache2::Upload;
my $req    = Apache2::Request->new($r);
my $upload = $req->upload("cgi-parameter-name");

The solution is to wrap the call to the $req->upload method in an eval{} block:

use Apache2::Request;
use Apache2::Upload;
my $req    = Apache2::Request->new($r);
my $upload; eval { $upload = $req->upload("cgi-parameter-name"); };

Although ignoring errors is normally a discouraged practice, in this case we're ignoring a situation where the user elected to not attach a file before submitting the HTML form (by way of the POST method with the enctype=multipart/form-data parameter).

Your code still needs to check whether a file was uploaded by testing whether the $upload variable is defined (consult the Apache2::Upload documentation for further information).