404 Not Found - One of the blob scatter parameters is missing

Below is a code snippet from the newest source root / gitweb / gitweb.perl

# preparing $fd and %diffinfo for git_patchset_body
# new style URI
if (defined $hash_base && defined $hash_parent_base) {
    if (defined $file_name) {
        # read raw output
        open $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
            $hash_parent_base, $hash_base,
            "--", (defined $file_parent ? $file_parent : ()), $file_name
            or die_error(500, "Open git-diff-tree failed");
        @difftree = map { chomp; $_ } <$fd>;
        close $fd
            or die_error(404, "Reading git-diff-tree failed");
        @difftree
            or die_error(404, "Blob diff not found");

    } elsif (defined $hash &&
             $hash =~ /[0-9a-fA-F]{40}/) {
        # try to find filename from $hash

        # read filtered raw output
        open $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
            $hash_parent_base, $hash_base, "--"
            or die_error(500, "Open git-diff-tree failed");
        @difftree =
            # ':100644 100644 03b21826... 3b93d5e7... M    ls-files.c'
            # $hash == to_id
            grep { /^:[0-7]{6} [0-7]{6} [0-9a-fA-F]{40} $hash/ }
            map { chomp; $_ } <$fd>;
        close $fd
            or die_error(404, "Reading git-diff-tree failed");
        @difftree
            or die_error(404, "Blob diff not found");

    } else {
        die_error(400, "Missing one of the blob diff parameters");
    }

    if (@difftree > 1) {
        die_error(400, "Ambiguous blob diff specification");
    }

    %diffinfo = parse_difftree_raw_line($difftree[0]);
    $file_parent ||= $diffinfo{'from_file'} || $file_name;
    $file_name   ||= $diffinfo{'to_file'};

    $hash_parent ||= $diffinfo{'from_id'};
    $hash        ||= $diffinfo{'to_id'};

    # non-textual hash id can be cached
    if ($hash_base =~ m/^[0-9a-fA-F]{40}$/ &&
        $hash_parent_base =~ m/^[0-9a-fA-F]{40}$/) {
        $expires = '+1d';
    }

    # open patch output
    open $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
        '-p', ($format eq 'html' ? "--full-index" : ()),
        $hash_parent_base, $hash_base,
        "--", (defined $file_parent ? $file_parent : ()), $file_name
        or die_error(500, "Open git-diff-tree failed");
}

# old/legacy style URI
if (!%diffinfo && # if new style URI failed
    defined $hash && defined $hash_parent) {
    # fake git-diff-tree raw output
    $diffinfo{'from_mode'} = $diffinfo{'to_mode'} = "blob";
    $diffinfo{'from_id'} = $hash_parent;
    $diffinfo{'to_id'}   = $hash;
    if (defined $file_name) {
        if (defined $file_parent) {
            $diffinfo{'status'} = '2';
            $diffinfo{'from_file'} = $file_parent;
            $diffinfo{'to_file'}   = $file_name;
        } else { # assume not renamed
            $diffinfo{'status'} = '1';
            $diffinfo{'from_file'} = $file_name;
            $diffinfo{'to_file'}   = $file_name;
        }
    } else { # no filename given
        $diffinfo{'status'} = '2';
        $diffinfo{'from_file'} = $hash_parent;
        $diffinfo{'to_file'}   = $hash;
    }

    # non-textual hash id can be cached
    if ($hash =~ m/^[0-9a-fA-F]{40}$/ &&
        $hash_parent =~ m/^[0-9a-fA-F]{40}$/) {
        $expires = '+1d';
    }

    # open patch output
    open $fd, "-|", git_cmd(), "diff", @diff_opts,
        '-p', ($format eq 'html' ? "--full-index" : ()),
        $hash_parent, $hash, "--"
        or die_error(500, "Open git-diff failed");
} else  {
    die_error(400, "Missing one of the blob diff parameters")
        unless %diffinfo;
}

      

        
        
        
      

    

And other code snippets (non-matching codes omitted) below are for parsing parameters:

our $file_name = $cgi->param('f');
our $hash = $cgi->param('h');
our $hash_parent = $cgi->param('hp');
our $hash_base = $cgi->param('hb');
our $hash_parent_base = $cgi->param('hpb');

      

        
        
        
      

    

Therefore the following is not correct:

defined $hash_base 

      

        
        
        
      

    

Unfortunately, that's all I got.
From the codes above, no Exception is expected.
However, your gitweb may not be the newest one. I suggest you check your sources.