diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 49b01d8..5351da2 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -386,7 +386,7 @@
 our $action = $cgi->param('a');
 if (defined $action) {
 	if ($action =~ m/[^0-9a-zA-Z\.\-_]/) {
-		die_error(undef, "Invalid action parameter");
+		die_error(400, "Invalid action parameter");
 	}
 }
 
@@ -399,21 +399,21 @@
 	    ($export_ok && !(-e "$projectroot/$project/$export_ok")) ||
 	    ($strict_export && !project_in_list($project))) {
 		undef $project;
-		die_error(undef, "No such project");
+		die_error(404, "No such project");
 	}
 }
 
 our $file_name = $cgi->param('f');
 if (defined $file_name) {
 	if (!validate_pathname($file_name)) {
-		die_error(undef, "Invalid file parameter");
+		die_error(400, "Invalid file parameter");
 	}
 }
 
 our $file_parent = $cgi->param('fp');
 if (defined $file_parent) {
 	if (!validate_pathname($file_parent)) {
-		die_error(undef, "Invalid file parent parameter");
+		die_error(400, "Invalid file parent parameter");
 	}
 }
 
@@ -421,21 +421,21 @@
 our $hash = $cgi->param('h');
 if (defined $hash) {
 	if (!validate_refname($hash)) {
-		die_error(undef, "Invalid hash parameter");
+		die_error(400, "Invalid hash parameter");
 	}
 }
 
 our $hash_parent = $cgi->param('hp');
 if (defined $hash_parent) {
 	if (!validate_refname($hash_parent)) {
-		die_error(undef, "Invalid hash parent parameter");
+		die_error(400, "Invalid hash parent parameter");
 	}
 }
 
 our $hash_base = $cgi->param('hb');
 if (defined $hash_base) {
 	if (!validate_refname($hash_base)) {
-		die_error(undef, "Invalid hash base parameter");
+		die_error(400, "Invalid hash base parameter");
 	}
 }
 
@@ -447,10 +447,10 @@
 if (defined @extra_options) {
 	foreach my $opt (@extra_options) {
 		if (not exists $allowed_options{$opt}) {
-			die_error(undef, "Invalid option parameter");
+			die_error(400, "Invalid option parameter");
 		}
 		if (not grep(/^$action$/, @{$allowed_options{$opt}})) {
-			die_error(undef, "Invalid option parameter for this action");
+			die_error(400, "Invalid option parameter for this action");
 		}
 	}
 }
@@ -458,7 +458,7 @@
 our $hash_parent_base = $cgi->param('hpb');
 if (defined $hash_parent_base) {
 	if (!validate_refname($hash_parent_base)) {
-		die_error(undef, "Invalid hash parent base parameter");
+		die_error(400, "Invalid hash parent base parameter");
 	}
 }
 
@@ -466,14 +466,14 @@
 our $page = $cgi->param('pg');
 if (defined $page) {
 	if ($page =~ m/[^0-9]/) {
-		die_error(undef, "Invalid page parameter");
+		die_error(400, "Invalid page parameter");
 	}
 }
 
 our $searchtype = $cgi->param('st');
 if (defined $searchtype) {
 	if ($searchtype =~ m/[^a-z]/) {
-		die_error(undef, "Invalid searchtype parameter");
+		die_error(400, "Invalid searchtype parameter");
 	}
 }
 
@@ -483,7 +483,7 @@
 our $search_regexp;
 if (defined $searchtext) {
 	if (length($searchtext) < 2) {
-		die_error(undef, "At least two characters are required for search parameter");
+		die_error(403, "At least two characters are required for search parameter");
 	}
 	$search_regexp = $search_use_regexp ? $searchtext : quotemeta $searchtext;
 }
@@ -580,11 +580,11 @@
 	}
 }
 if (!defined($actions{$action})) {
-	die_error(undef, "Unknown action");
+	die_error(400, "Unknown action");
 }
 if ($action !~ m/^(opml|project_list|project_index)$/ &&
     !$project) {
-	die_error(undef, "Project needed");
+	die_error(400, "Project needed");
 }
 $actions{$action}->();
 exit;
@@ -1665,7 +1665,7 @@
 	$path =~ s,/+$,,;
 
 	open my $fd, "-|", git_cmd(), "ls-tree", $base, "--", $path
-		or die_error(undef, "Open git-ls-tree failed");
+		or die_error(500, "Open git-ls-tree failed");
 	my $line = <$fd>;
 	close $fd or return undef;
 
@@ -2127,7 +2127,7 @@
 		"--max-count=1",
 		$commit_id,
 		"--",
-		or die_error(undef, "Open git-rev-list failed");
+		or die_error(500, "Open git-rev-list failed");
 	%co = parse_commit_text(<$fd>, 1);
 	close $fd;
 
@@ -2152,7 +2152,7 @@
 		$commit_id,
 		"--",
 		($filename ? ($filename) : ())
-		or die_error(undef, "Open git-rev-list failed");
+		or die_error(500, "Open git-rev-list failed");
 	while (my $line = <$fd>) {
 		my %co = parse_commit_text($line);
 		push @cos, \%co;
@@ -2672,11 +2672,26 @@
 	      "</html>";
 }
 
+# die_error(<http_status_code>, <error_message>)
+# Example: die_error(404, 'Hash not found')
+# By convention, use the following status codes (as defined in RFC 2616):
+# 400: Invalid or missing CGI parameters, or
+#      requested object exists but has wrong type.
+# 403: Requested feature (like "pickaxe" or "snapshot") not enabled on
+#      this server or project.
+# 404: Requested object/revision/project doesn't exist.
+# 500: The server isn't configured properly, or
+#      an internal error occurred (e.g. failed assertions caused by bugs), or
+#      an unknown error occurred (e.g. the git binary died unexpectedly).
 sub die_error {
-	my $status = shift || "403 Forbidden";
-	my $error = shift || "Malformed query, file missing or permission denied";
+	my $status = shift || 500;
+	my $error = shift || "Internal server error";
 
-	git_header_html($status);
+	my %http_responses = (400 => '400 Bad Request',
+			      403 => '403 Forbidden',
+			      404 => '404 Not Found',
+			      500 => '500 Internal Server Error');
+	git_header_html($http_responses{$status});
 	print <<EOF;
 <div class="page_body">
 <br /><br />
@@ -3924,12 +3939,12 @@
 sub git_project_list {
 	my $order = $cgi->param('o');
 	if (defined $order && $order !~ m/none|project|descr|owner|age/) {
-		die_error(undef, "Unknown order parameter");
+		die_error(400, "Unknown order parameter");
 	}
 
 	my @list = git_get_projects_list();
 	if (!@list) {
-		die_error(undef, "No projects found");
+		die_error(404, "No projects found");
 	}
 
 	git_header_html();
@@ -3947,12 +3962,12 @@
 sub git_forks {
 	my $order = $cgi->param('o');
 	if (defined $order && $order !~ m/none|project|descr|owner|age/) {
-		die_error(undef, "Unknown order parameter");
+		die_error(400, "Unknown order parameter");
 	}
 
 	my @list = git_get_projects_list($project);
 	if (!@list) {
-		die_error(undef, "No forks found");
+		die_error(404, "No forks found");
 	}
 
 	git_header_html();
@@ -4081,7 +4096,7 @@
 	my %tag = parse_tag($hash);
 
 	if (! %tag) {
-		die_error(undef, "Unknown tag object");
+		die_error(404, "Unknown tag object");
 	}
 
 	git_print_header_div('commit', esc_html($tag{'name'}), $hash);
@@ -4117,26 +4132,25 @@
 	my $fd;
 	my $ftype;
 
-	my ($have_blame) = gitweb_check_feature('blame');
-	if (!$have_blame) {
-		die_error('403 Permission denied', "Permission denied");
-	}
-	die_error('404 Not Found', "File name not defined") if (!$file_name);
+	gitweb_check_feature('blame')
+	    or die_error(403, "Blame view not allowed");
+
+	die_error(400, "No file name given") unless $file_name;
 	$hash_base ||= git_get_head_hash($project);
-	die_error(undef, "Couldn't find base commit") unless ($hash_base);
+	die_error(404, "Couldn't find base commit") unless ($hash_base);
 	my %co = parse_commit($hash_base)
-		or die_error(undef, "Reading commit failed");
+		or die_error(404, "Commit not found");
 	if (!defined $hash) {
 		$hash = git_get_hash_by_path($hash_base, $file_name, "blob")
-			or die_error(undef, "Error looking up file");
+			or die_error(404, "Error looking up file");
 	}
 	$ftype = git_get_type($hash);
 	if ($ftype !~ "blob") {
-		die_error('400 Bad Request', "Object is not a blob");
+		die_error(400, "Object is not a blob");
 	}
 	open ($fd, "-|", git_cmd(), "blame", '-p', '--',
 	      $file_name, $hash_base)
-		or die_error(undef, "Open git-blame failed");
+		or die_error(500, "Open git-blame failed");
 	git_header_html();
 	my $formats_nav =
 		$cgi->a({-href => href(action=>"blob", -replay=>1)},
@@ -4198,7 +4212,7 @@
 			print "</td>\n";
 		}
 		open (my $dd, "-|", git_cmd(), "rev-parse", "$full_rev^")
-			or die_error(undef, "Open git-rev-parse failed");
+			or die_error(500, "Open git-rev-parse failed");
 		my $parent_commit = <$dd>;
 		close $dd;
 		chomp($parent_commit);
@@ -4352,9 +4366,9 @@
 		if (defined $file_name) {
 			my $base = $hash_base || git_get_head_hash($project);
 			$hash = git_get_hash_by_path($base, $file_name, "blob")
-				or die_error(undef, "Error lookup file");
+				or die_error(404, "Cannot find file");
 		} else {
-			die_error(undef, "No file name defined");
+			die_error(400, "No file name defined");
 		}
 	} elsif ($hash =~ m/^[0-9a-fA-F]{40}$/) {
 		# blobs defined by non-textual hash id's can be cached
@@ -4362,7 +4376,7 @@
 	}
 
 	open my $fd, "-|", git_cmd(), "cat-file", "blob", $hash
-		or die_error(undef, "Open git-cat-file blob '$hash' failed");
+		or die_error(500, "Open git-cat-file blob '$hash' failed");
 
 	# content-type (can include charset)
 	$type = blob_contenttype($fd, $file_name, $type);
@@ -4394,9 +4408,9 @@
 		if (defined $file_name) {
 			my $base = $hash_base || git_get_head_hash($project);
 			$hash = git_get_hash_by_path($base, $file_name, "blob")
-				or die_error(undef, "Error lookup file");
+				or die_error(404, "Cannot find file");
 		} else {
-			die_error(undef, "No file name defined");
+			die_error(400, "No file name defined");
 		}
 	} elsif ($hash =~ m/^[0-9a-fA-F]{40}$/) {
 		# blobs defined by non-textual hash id's can be cached
@@ -4405,7 +4419,7 @@
 
 	my ($have_blame) = gitweb_check_feature('blame');
 	open my $fd, "-|", git_cmd(), "cat-file", "blob", $hash
-		or die_error(undef, "Couldn't cat $file_name, $hash");
+		or die_error(500, "Couldn't cat $file_name, $hash");
 	my $mimetype = blob_mimetype($fd, $file_name);
 	if ($mimetype !~ m!^(?:text/|image/(?:gif|png|jpeg)$)! && -B $fd) {
 		close $fd;
@@ -4486,9 +4500,9 @@
 	}
 	$/ = "\0";
 	open my $fd, "-|", git_cmd(), "ls-tree", '-z', $hash
-		or die_error(undef, "Open git-ls-tree failed");
+		or die_error(500, "Open git-ls-tree failed");
 	my @entries = map { chomp; $_ } <$fd>;
-	close $fd or die_error(undef, "Reading tree failed");
+	close $fd or die_error(404, "Reading tree failed");
 	$/ = "\n";
 
 	my $refs = git_get_references();
@@ -4578,16 +4592,16 @@
 
 	my $format = $cgi->param('sf');
 	if (!@supported_fmts) {
-		die_error('403 Permission denied', "Permission denied");
+		die_error(403, "Snapshots not allowed");
 	}
 	# default to first supported snapshot format
 	$format ||= $supported_fmts[0];
 	if ($format !~ m/^[a-z0-9]+$/) {
-		die_error(undef, "Invalid snapshot format parameter");
+		die_error(400, "Invalid snapshot format parameter");
 	} elsif (!exists($known_snapshot_formats{$format})) {
-		die_error(undef, "Unknown snapshot format");
+		die_error(400, "Unknown snapshot format");
 	} elsif (!grep($_ eq $format, @supported_fmts)) {
-		die_error(undef, "Unsupported snapshot format");
+		die_error(403, "Unsupported snapshot format");
 	}
 
 	if (!defined $hash) {
@@ -4615,7 +4629,7 @@
 		-status => '200 OK');
 
 	open my $fd, "-|", $cmd
-		or die_error(undef, "Execute git-archive failed");
+		or die_error(500, "Execute git-archive failed");
 	binmode STDOUT, ':raw';
 	print <$fd>;
 	binmode STDOUT, ':utf8'; # as set at the beginning of gitweb.cgi
@@ -4683,10 +4697,8 @@
 
 sub git_commit {
 	$hash ||= $hash_base || "HEAD";
-	my %co = parse_commit($hash);
-	if (!%co) {
-		die_error(undef, "Unknown commit object");
-	}
+	my %co = parse_commit($hash)
+	    or die_error(404, "Unknown commit object");
 	my %ad = parse_date($co{'author_epoch'}, $co{'author_tz'});
 	my %cd = parse_date($co{'committer_epoch'}, $co{'committer_tz'});
 
@@ -4726,9 +4738,9 @@
 		@diff_opts,
 		(@$parents <= 1 ? $parent : '-c'),
 		$hash, "--"
-		or die_error(undef, "Open git-diff-tree failed");
+		or die_error(500, "Open git-diff-tree failed");
 	@difftree = map { chomp; $_ } <$fd>;
-	close $fd or die_error(undef, "Reading git-diff-tree failed");
+	close $fd or die_error(404, "Reading git-diff-tree failed");
 
 	# non-textual hash id's can be cached
 	my $expires;
@@ -4821,33 +4833,33 @@
 
 		open my $fd, "-|", quote_command(
 			git_cmd(), 'cat-file', '-t', $object_id) . ' 2> /dev/null'
-			or die_error('404 Not Found', "Object does not exist");
+			or die_error(404, "Object does not exist");
 		$type = <$fd>;
 		chomp $type;
 		close $fd
-			or die_error('404 Not Found', "Object does not exist");
+			or die_error(404, "Object does not exist");
 
 	# - hash_base and file_name
 	} elsif ($hash_base && defined $file_name) {
 		$file_name =~ s,/+$,,;
 
 		system(git_cmd(), "cat-file", '-e', $hash_base) == 0
-			or die_error('404 Not Found', "Base object does not exist");
+			or die_error(404, "Base object does not exist");
 
 		# here errors should not hapen
 		open my $fd, "-|", git_cmd(), "ls-tree", $hash_base, "--", $file_name
-			or die_error(undef, "Open git-ls-tree failed");
+			or die_error(500, "Open git-ls-tree failed");
 		my $line = <$fd>;
 		close $fd;
 
 		#'100644 blob 0fa3f3a66fb6a137f6ec2c19351ed4d807070ffa	panic.c'
 		unless ($line && $line =~ m/^([0-9]+) (.+) ([0-9a-fA-F]{40})\t/) {
-			die_error('404 Not Found', "File or directory for given base does not exist");
+			die_error(404, "File or directory for given base does not exist");
 		}
 		$type = $2;
 		$hash = $3;
 	} else {
-		die_error('404 Not Found', "Not enough information to find object");
+		die_error(400, "Not enough information to find object");
 	}
 
 	print $cgi->redirect(-uri => href(action=>$type, -full=>1,
@@ -4872,12 +4884,12 @@
 			open $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
 				$hash_parent_base, $hash_base,
 				"--", (defined $file_parent ? $file_parent : ()), $file_name
-				or die_error(undef, "Open git-diff-tree failed");
+				or die_error(500, "Open git-diff-tree failed");
 			@difftree = map { chomp; $_ } <$fd>;
 			close $fd
-				or die_error(undef, "Reading git-diff-tree failed");
+				or die_error(404, "Reading git-diff-tree failed");
 			@difftree
-				or die_error('404 Not Found', "Blob diff not found");
+				or die_error(404, "Blob diff not found");
 
 		} elsif (defined $hash &&
 		         $hash =~ /[0-9a-fA-F]{40}/) {
@@ -4886,23 +4898,23 @@
 			# read filtered raw output
 			open $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
 				$hash_parent_base, $hash_base, "--"
-				or die_error(undef, "Open git-diff-tree failed");
+				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(undef, "Reading git-diff-tree failed");
+				or die_error(404, "Reading git-diff-tree failed");
 			@difftree
-				or die_error('404 Not Found', "Blob diff not found");
+				or die_error(404, "Blob diff not found");
 
 		} else {
-			die_error('404 Not Found', "Missing one of the blob diff parameters");
+			die_error(400, "Missing one of the blob diff parameters");
 		}
 
 		if (@difftree > 1) {
-			die_error('404 Not Found', "Ambiguous blob diff specification");
+			die_error(400, "Ambiguous blob diff specification");
 		}
 
 		%diffinfo = parse_difftree_raw_line($difftree[0]);
@@ -4923,7 +4935,7 @@
 			'-p', ($format eq 'html' ? "--full-index" : ()),
 			$hash_parent_base, $hash_base,
 			"--", (defined $file_parent ? $file_parent : ()), $file_name
-			or die_error(undef, "Open git-diff-tree failed");
+			or die_error(500, "Open git-diff-tree failed");
 	}
 
 	# old/legacy style URI
@@ -4959,9 +4971,9 @@
 		open $fd, "-|", git_cmd(), "diff", @diff_opts,
 			'-p', ($format eq 'html' ? "--full-index" : ()),
 			$hash_parent, $hash, "--"
-			or die_error(undef, "Open git-diff failed");
+			or die_error(500, "Open git-diff failed");
 	} else  {
-		die_error('404 Not Found', "Missing one of the blob diff parameters")
+		die_error(400, "Missing one of the blob diff parameters")
 			unless %diffinfo;
 	}
 
@@ -4994,7 +5006,7 @@
 		print "X-Git-Url: " . $cgi->self_url() . "\n\n";
 
 	} else {
-		die_error(undef, "Unknown blobdiff format");
+		die_error(400, "Unknown blobdiff format");
 	}
 
 	# patch
@@ -5029,10 +5041,8 @@
 sub git_commitdiff {
 	my $format = shift || 'html';
 	$hash ||= $hash_base || "HEAD";
-	my %co = parse_commit($hash);
-	if (!%co) {
-		die_error(undef, "Unknown commit object");
-	}
+	my %co = parse_commit($hash)
+	    or die_error(404, "Unknown commit object");
 
 	# choose format for commitdiff for merge
 	if (! defined $hash_parent && @{$co{'parents'}} > 1) {
@@ -5114,7 +5124,7 @@
 		open $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
 			"--no-commit-id", "--patch-with-raw", "--full-index",
 			$hash_parent_param, $hash, "--"
-			or die_error(undef, "Open git-diff-tree failed");
+			or die_error(500, "Open git-diff-tree failed");
 
 		while (my $line = <$fd>) {
 			chomp $line;
@@ -5126,10 +5136,10 @@
 	} elsif ($format eq 'plain') {
 		open $fd, "-|", git_cmd(), "diff-tree", '-r', @diff_opts,
 			'-p', $hash_parent_param, $hash, "--"
-			or die_error(undef, "Open git-diff-tree failed");
+			or die_error(500, "Open git-diff-tree failed");
 
 	} else {
-		die_error(undef, "Unknown commitdiff format");
+		die_error(400, "Unknown commitdiff format");
 	}
 
 	# non-textual hash id's can be cached
@@ -5212,19 +5222,15 @@
 		$page = 0;
 	}
 	my $ftype;
-	my %co = parse_commit($hash_base);
-	if (!%co) {
-		die_error(undef, "Unknown commit object");
-	}
+	my %co = parse_commit($hash_base)
+	    or die_error(404, "Unknown commit object");
 
 	my $refs = git_get_references();
 	my $limit = sprintf("--max-count=%i", (100 * ($page+1)));
 
 	my @commitlist = parse_commits($hash_base, 101, (100 * $page),
-	                               $file_name, "--full-history");
-	if (!@commitlist) {
-		die_error('404 Not Found', "No such file or directory on given branch");
-	}
+	                               $file_name, "--full-history")
+	    or die_error(404, "No such file or directory on given branch");
 
 	if (!defined $hash && defined $file_name) {
 		# some commits could have deleted file in question,
@@ -5238,7 +5244,7 @@
 		$ftype = git_get_type($hash);
 	}
 	if (!defined $ftype) {
-		die_error(undef, "Unknown type of object");
+		die_error(500, "Unknown type of object");
 	}
 
 	my $paging_nav = '';
@@ -5276,19 +5282,16 @@
 }
 
 sub git_search {
-	my ($have_search) = gitweb_check_feature('search');
-	if (!$have_search) {
-		die_error('403 Permission denied', "Permission denied");
-	}
+	gitweb_check_feature('search') or die_error(403, "Search is disabled");
 	if (!defined $searchtext) {
-		die_error(undef, "Text field empty");
+		die_error(400, "Text field is empty");
 	}
 	if (!defined $hash) {
 		$hash = git_get_head_hash($project);
 	}
 	my %co = parse_commit($hash);
 	if (!%co) {
-		die_error(undef, "Unknown commit object");
+		die_error(404, "Unknown commit object");
 	}
 	if (!defined $page) {
 		$page = 0;
@@ -5298,16 +5301,12 @@
 	if ($searchtype eq 'pickaxe') {
 		# pickaxe may take all resources of your box and run for several minutes
 		# with every query - so decide by yourself how public you make this feature
-		my ($have_pickaxe) = gitweb_check_feature('pickaxe');
-		if (!$have_pickaxe) {
-			die_error('403 Permission denied', "Permission denied");
-		}
+		gitweb_check_feature('pickaxe')
+		    or die_error(403, "Pickaxe is disabled");
 	}
 	if ($searchtype eq 'grep') {
-		my ($have_grep) = gitweb_check_feature('grep');
-		if (!$have_grep) {
-			die_error('403 Permission denied', "Permission denied");
-		}
+		gitweb_check_feature('grep')
+		    or die_error(403, "Grep is disabled");
 	}
 
 	git_header_html();
@@ -5581,7 +5580,7 @@
 	# Atom: http://www.atomenabled.org/developers/syndication/
 	# RSS:  http://www.notestips.com/80256B3A007F2692/1/NAMO5P9UPQ
 	if ($format ne 'rss' && $format ne 'atom') {
-		die_error(undef, "Unknown web feed format");
+		die_error(400, "Unknown web feed format");
 	}
 
 	# log/feed of current (HEAD) branch, log of given branch, history of file/directory