diff --git a/common/code/boost.php b/common/code/boost.php
index 7c56ffa0..02b70617 100644
--- a/common/code/boost.php
+++ b/common/code/boost.php
@@ -10,9 +10,11 @@ function html_encode($text) {
     return htmlentities($text, ENT_COMPAT, 'UTF-8');
 }
 
+class BoostException extends RuntimeException {}
+
 spl_autoload_register(function($name) {
     if (!preg_match('@^[A-Za-z0-9\\\\_]*$@', $name)) {
-        throw new \RuntimeException("Invalid autoload name: {$name}");
+        throw new BoostException("Invalid autoload name: {$name}");
     }
 
     $file_path = __DIR__.'/'
diff --git a/common/code/boost_book_parser.php b/common/code/boost_book_parser.php
index 5fa2a1ed..f0b9fdc5 100644
--- a/common/code/boost_book_parser.php
+++ b/common/code/boost_book_parser.php
@@ -11,7 +11,7 @@ class BoostBookParser {
         $state = new BoostBookParser_State();
         xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0);
         if (!xml_parse_into_struct($parser, file_get_contents($filename), $state->values, $state->index)) {
-            die("Error parsing XML");
+            throw new BoostException("Error parsing XML");
         }
         xml_parser_free($parser);
 
@@ -77,7 +77,7 @@ class BoostBookParser {
         if (method_exists($this, $name)) {
             return $this->{$name}($state);
         } else {
-            die("Unknown node type {$state->get_tag()}\n");
+            throw new BoostException("Unknown node type {$state->get_tag()}");
         }
     }
 
@@ -92,11 +92,11 @@ class BoostBookParser {
                 $result .= $this->x($state);
             }
             if ($state->get_tag() != $tag) {
-                die("Parse error\n");
+                throw new BoostException("Parse error");
             }
             return $result;
         default:
-            die("Invalid node in convert_children_to_xhtml: {$state->get_type()}.\n");
+            throw new BoostException("Invalid node in convert_children_to_xhtml: {$state->get_type()}");
         }
     }
 
@@ -108,7 +108,7 @@ class BoostBookParser {
         case 'open':
             break;
         case 'default':
-            die("Error parsing article.\n");
+            throw new BoostException("Error parsing article");
         }
         for(++$state->pos; $state->get_type() != 'close'; ++$state->pos) {
             if (in_array($state->get_tag(), array('title', 'articleinfo'))) {
@@ -283,7 +283,7 @@ class BoostBookParser {
             }
             break;
         default:
-            die("Invalid node in skip_to_end_of_tag.\n");
+            throw new BoostException("Invalid node in skip_to_end_of_tag");
         }
     }
 
@@ -301,7 +301,7 @@ class BoostBookParser {
             }
             return;
         default:
-            die("Invalid node in skip_to_end_of_tag.\n");
+            throw new BoostException("Invalid node in skip_to_end_of_tag");
         }
     }
 
@@ -330,7 +330,7 @@ class BoostBookParser {
             }
             return $found;
         default:
-            die("Invalid node in skip_to_end_of_tag.\n");
+            throw new BoostException("Invalid node in skip_to_end_of_tag");
         }
     }
 
diff --git a/common/code/boost_libraries.php b/common/code/boost_libraries.php
index d8cef301..9e9d5e3d 100644
--- a/common/code/boost_libraries.php
+++ b/common/code/boost_libraries.php
@@ -55,7 +55,7 @@ class BoostLibraries
         xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0);
         xml_parser_set_option($parser, XML_OPTION_SKIP_WHITE, 1);
         if (!xml_parse_into_struct($parser, $xml, $values)) {
-            die("Error parsing XML");
+            throw new BoostLibraries_DecodeException("Error parsing XML", $xml);
         }
         xml_parser_free($parser);
 
@@ -121,9 +121,9 @@ class BoostLibraries
                     {
                         $value = isset($val['value']) ? trim($val['value']) : false;
                         if($value && $value != 'true' && $value != 'false') {
-                            echo 'Invalid value for ',html_encode($val['tag']),
-                                ': ', $value, "\n";
-                            exit(0);
+                            throw new BoostLibraries_DecodeException(
+                                'Invalid value for ',$val['tag'].': '.$value,
+                                $xml);
                         }
                         $lib[$val['tag']] = ($value == 'true');
                     }
@@ -140,8 +140,8 @@ class BoostLibraries
                     }
                     break;
                     default:
-                        echo 'Invalid tag: ', html_encode($val['tag']), "\n";
-                        exit(0);
+                    throw new BoostLibraries_DecodeException(
+                        'Invalid tag: '.$val['tag'], $xml);
                 }
             }
             else if ($val['tag'] == 'library' && $val['type'] == 'close' && $lib)
@@ -151,8 +151,8 @@ class BoostLibraries
             }
             else
             {
-                echo 'Invalid tag: ', html_encode($val['tag']), "\n";
-                exit(0);
+                throw new BoostLibraries_DecodeException(
+                    'Invalid tag: '.$val['tag'], $xml);
             }
         }
 
@@ -167,7 +167,7 @@ class BoostLibraries
 
         $import = json_decode($json, true);
         if (!$import) {
-            throw new library_decode_exception("Error decoding json.", $json);
+            throw new BoostLibraries_DecodeException("Error decoding json.", $json);
         }
 
         if ($json[0] == '{') {
@@ -231,8 +231,7 @@ class BoostLibraries
                 BoostVersion::from($update_version) :
                 BoostVersion::unreleased();
             if (!$update_version->is_release()) {
-                throw new BoostLibraries_exception(
-                        "No version info for {$details['key']}");
+                throw new BoostLibraries_Exception("No version info for {$details['key']}");
             }
             if (isset($details['update-version'])) {
                 unset($details['update-version']);
@@ -285,7 +284,6 @@ class BoostLibraries
      * Update the libraries from an array of BoostLibrary.
      *
      * @param array $update
-     * @throws BoostLibraries_exception
      */
     public function update($update_version = null, $update = null) {
         $this->update_start($update_version);
@@ -626,8 +624,7 @@ class BoostLibraries
         foreach($libs as $key => $library) {
             foreach($library['category'] as $category) {
                 if(!isset($this->categories[$category])) {
-                    echo 'Unknown category: ', html_encode($category), "\n";
-                    exit(0);
+                    throw new BoostLibraries_Exception('Unknown category: '.$category);
                 }
                 $categories[$category]['libraries'][] = $library;
             }
@@ -752,8 +749,8 @@ class BoostLibraries_XMLWriter {
     }
 }
 
-class BoostLibraries_exception extends RuntimeException {}
-class library_decode_exception extends BoostLibraries_exception {
+class BoostLibraries_Exception extends BoostException {}
+class BoostLibraries_DecodeException extends BoostLibraries_Exception {
     private $content = '';
 
     function __construct($message, $content) {
diff --git a/common/code/boost_library.php b/common/code/boost_library.php
index 13ac3fae..9b0e6141 100644
--- a/common/code/boost_library.php
+++ b/common/code/boost_library.php
@@ -21,7 +21,7 @@ class BoostLibrary
         $json = trim($json);
         $libs = json_decode($json, true);
         if (!is_array($libs)) {
-            throw new library_decode_exception("Error decoding json.", $json);
+            throw new BoostLibraries_DecodeException("Error decoding json.", $json);
         }
         if ($json[0] == '{') {
             $libs = array($libs);
diff --git a/common/code/boost_maintainers.php b/common/code/boost_maintainers.php
index 702be83f..adb95a90 100644
--- a/common/code/boost_maintainers.php
+++ b/common/code/boost_maintainers.php
@@ -37,8 +37,7 @@ class BoostMaintainers
 
             $matches = null;
             if (!preg_match('@^([^\s]+)\s*(.*)$@', $line, $matches)) {
-                echo "Unable to parse line: {$line}\n";
-                exit(1);
+                throw new BoostException("Unable to parse line: {$line}");
             }
 
             $key = trim($matches[1]);
diff --git a/common/code/boost_pages.php b/common/code/boost_pages.php
index 43182a40..4e8f36dd 100644
--- a/common/code/boost_pages.php
+++ b/common/code/boost_pages.php
@@ -19,9 +19,7 @@ class BoostPages {
             $this->release_data = json_decode(
                 file_get_contents($this->release_file), true);
             if (is_null($this->release_data)) {
-                // Q: Exception? Fallback?
-                echo "Error decoding release data.\n";
-                exit(0);
+                throw new BoostException("Error decoding release data.");
             }
         }
 
@@ -101,7 +99,7 @@ class BoostPages {
         $record->last_modified = new DateTime();
 
         if (!in_array($record->type, array('release', 'page'))) {
-            throw new RuntimeException("Unknown record type: ".$record->type);
+            throw new BoostException("Unknown record type: ".$record->type);
         }
     }
 
@@ -242,8 +240,7 @@ class BoostPages_Page {
                 : ($this->pub_date ? 'released' : 'dev');
 
             if (!preg_match('@^(released|dev|beta) *(\d*)$@', $release_status, $release_parts)) {
-                echo "Error: Unknown release status: {$this->array_get($release_data, 'release_status')}.\n";
-                exit(0);
+                throw new BoostException("Error: Unknown release status: {$this->array_get($release_data, 'release_status')}.");
             }
 
             if ($release_parts[2] && $release_parts[1] != 'beta') {
diff --git a/common/code/boost_simple_template.php b/common/code/boost_simple_template.php
index 487e113a..c9581443 100644
--- a/common/code/boost_simple_template.php
+++ b/common/code/boost_simple_template.php
@@ -16,7 +16,7 @@ class BoostSimpleTemplate {
 
         $nodes = $context->partial_loader->load($path);
         if (!$nodes) {
-            throw new BoostSimpleTemplateException("File not found: {$path}");
+            throw new BoostSimpleTemplate_Exception("File not found: {$path}");
         }
 
         return self::interpret($context, $nodes);
@@ -71,7 +71,7 @@ class BoostSimpleTemplate {
             );
 
             if (self::match_exists($match, 'error')) {
-                throw new BoostSimpleTemplateException("Invalid/unsupported tag", $match['tag'][1]);
+                throw new BoostSimpleTemplate_Exception("Invalid/unsupported tag", $match['tag'][1]);
             }
             else if (self::match_exists($match, 'unescaped')) {
                 $node['type'] = '&';
@@ -129,7 +129,7 @@ class BoostSimpleTemplate {
             case '/':
                 $top = array_pop($stack);
                 if (!$top || $top['node']['symbol'] !== $node['symbol']) {
-                    throw new BoostSimpleTemplateException("Mismatched close tag", $node['offset']);
+                    throw new BoostSimpleTemplate_Exception("Mismatched close tag", $node['offset']);
                 }
                 $node = $top['node'];
                 $node['contents'] = $nodes;
@@ -153,7 +153,7 @@ class BoostSimpleTemplate {
 
         if ($stack) {
             $top = end($stack);
-            throw new BoostSimpleTemplateException("Unclosed tag: {$top['node']['symbol']}", $top['node']['offset']);
+            throw new BoostSimpleTemplate_Exception("Unclosed tag: {$top['node']['symbol']}", $top['node']['offset']);
         }
 
         $end = substr($template, $offset);
@@ -382,7 +382,7 @@ class BoostSimpleTemplate_Context {
     }
 }
 
-class BoostSimpleTemplateException extends \RuntimeException {
+class BoostSimpleTemplate_Exception extends BoostException {
     var $offset;
     
     function __construct($message, $offset = null) {
diff --git a/common/code/boost_site_tools.php b/common/code/boost_site_tools.php
index 2831eb2a..e0e2d2cd 100644
--- a/common/code/boost_site_tools.php
+++ b/common/code/boost_site_tools.php
@@ -252,7 +252,7 @@ class BoostSiteTools_Upgrades {
         $filename = $site_tools->root.'/generated/state/version.txt';
         $file_contents = trim(file_get_contents($filename));
         if (!preg_match('@^[0-9]+$@', $file_contents)) {
-            throw new RuntimeException("Error reading state version");
+            throw new BoostException("Error reading state version");
         }
         $current_version = intval($file_contents);
         foreach (self::$versions as $version => $upgrade_function) {
@@ -265,6 +265,6 @@ class BoostSiteTools_Upgrades {
     }
 
     static function old_upgrade() {
-        throw new RuntimeException("Old unsupported data version.");
+        throw new BoostException("Old unsupported data version.");
     }
 }
diff --git a/common/code/boost_state.php b/common/code/boost_state.php
index 8f7a0549..c39b5937 100644
--- a/common/code/boost_state.php
+++ b/common/code/boost_state.php
@@ -4,7 +4,7 @@
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt || http://www.boost.org/LICENSE_1_0.txt)
 
-class BoostStateParseError extends RuntimeException {}
+class BoostState_ParseError extends BoostException {}
 
 class BoostState {
     static function load($file_path) {
@@ -21,12 +21,12 @@ class BoostState {
                     $record_key = rtrim(fgets($file));
                     if (!$record_key) {
                         fclose($file);
-                        throw new BoostStateParseError();
+                        throw new BoostState_ParseError();
                     }
                     $state[$record_key] = self::read_record($file);
                 } else {
                     fclose($file);
-                    throw new BoostStateParseError();
+                    throw new BoostState_ParseError();
                 }
             }
             fclose($file);
@@ -43,14 +43,14 @@ class BoostState {
         $c = fgetc($file);
 
         while (true) {
-            if (!$c) { throw new BoostStateParseError(); }
+            if (!$c) { throw new BoostState_ParseError(); }
 
             if ($c == ')') {
-                if (fgets($file) != "\n") { throw new BoostStateParseError(); }
+                if (fgets($file) != "\n") { throw new BoostState_ParseError(); }
                 return $record;
             }
 
-            if ($c != '-') { throw new BoostStateParseError(); }
+            if ($c != '-') { throw new BoostState_ParseError(); }
 
             $key = rtrim(fgets($file));
             $c = fgetc($file);
@@ -80,7 +80,7 @@ class BoostState {
                 $record["$key"] = new DateTime(fgets($file));
                 $c = fgetc($file);
             } else {
-                throw new BoostStateParseError();
+                throw new BoostState_ParseError();
             }
         }
     }
diff --git a/common/code/boost_super_project.php b/common/code/boost_super_project.php
index 9526ec47..0ad87275 100644
--- a/common/code/boost_super_project.php
+++ b/common/code/boost_super_project.php
@@ -49,7 +49,7 @@ class BoostSuperProject {
                 $modules[$matches[1]][$matches[2]] = $matches[3];
             }
             else {
-                throw new RuntimeException("Unsupported config line: {$line}");
+                throw new BoostException("Unsupported config line: {$line}");
             }
         }
 
@@ -88,7 +88,7 @@ class BoostSuperProject {
     }
 }
 
-class ProcessError extends RuntimeException {
+class ProcessError extends BoostException {
     public $error_code;
 
     function __construct($error_code) {
diff --git a/common/code/boost_version.php b/common/code/boost_version.php
index ef3e5456..7a1dc4d8 100644
--- a/common/code/boost_version.php
+++ b/common/code/boost_version.php
@@ -113,7 +113,7 @@ class BoostVersion {
             }
         }
         else {
-            die("Can't convert to BoostVersion.\n");
+            throw new BoostVersion_Exception("Can't convert to BoostVersion.");
         }
     }
 
@@ -123,7 +123,7 @@ class BoostVersion {
      */
     static function current() {
         if (BoostVersion::$current == null)
-            die("Version not set.");
+            throw new BoostVersion_Exception("Version not set.");
         return BoostVersion::$current;
     }
 
@@ -255,9 +255,9 @@ class BoostVersion {
 
     static function set_current($major, $minor, $point) {
         if (self::$current != null)
-            die("Setting current version twice.");
+            throw new BoostVersion_Exception("Setting current version twice.");
         self::$current = self::release($major, $minor, $point);
     }
 }
 
-class BoostVersion_Exception extends RuntimeException {}
+class BoostVersion_Exception extends BoostException {}
diff --git a/doc/generate.php b/doc/generate.php
index a1689319..82baecd3 100644
--- a/doc/generate.php
+++ b/doc/generate.php
@@ -8,6 +8,7 @@ require_once(__DIR__.'/../common/code/bootstrap.php');
 
 function main($args) {
     if (!array_key_exists('page', $args)) {
+        header($_SERVER['SERVER_PROTOCOL'] . ' 400 Missing page argument', true, 400);
         echo "Missing page argument.\n";
         exit(1);
     }
@@ -18,6 +19,7 @@ function main($args) {
         $page->display();
         break;
     default:
+        header($_SERVER['SERVER_PROTOCOL'] . ' 404 Page not found', true, 404);
         echo "Unknown page: ", htmlentities($args['page']), "\n";
         exit(1);
     }
diff --git a/doc/libraries.json.php b/doc/libraries.json.php
index e227d43d..9afa7927 100644
--- a/doc/libraries.json.php
+++ b/doc/libraries.json.php
@@ -1,12 +1,13 @@
 <?php
 
-require_once(__DIR__.'/../common/code/boost.php');
+require_once(__DIR__.'/../common/code/bootstrap.php');
 
 if (isset($_GET['version'])) {
     try {
         $version = BoostVersion::from($_GET['version']);
     }
     catch (BoostVersion_Exception $e) {
+        header($_SERVER['SERVER_PROTOCOL'] . ' 500 Internal Server Error', true, 500);
         echo json_encode(Array(
             'error' => $e->getMessage(),
         ));
diff --git a/doc/libraries.php b/doc/libraries.php
index eb1f2d1d..826b2694 100644
--- a/doc/libraries.php
+++ b/doc/libraries.php
@@ -53,7 +53,7 @@ class LibraryPage {
             $filter_value = '';
 
             if (!preg_match('@^[-_a-zA-Z0-9]+$@', $view_value)) {
-                die('Invalid view value.');
+                throw new BoostException('Invalid view value.');
             }
 
             if (strpos($view_value, 'filtered_') === 0) {
diff --git a/webhook/github-webhook.php b/webhook/github-webhook.php
index 86f54557..7ed1b6f0 100644
--- a/webhook/github-webhook.php
+++ b/webhook/github-webhook.php
@@ -5,7 +5,9 @@
 require_once(__DIR__.'/../common/code/boost_config.php');
 
 if (!defined('BOOST_TASKS_DIR')) {
-    die("Tasks directory not set.");
+    header($_SERVER['SERVER_PROTOCOL'] . ' 500 Internal Server Error', true, 500);
+    echo "Tasks directory not set.";
+    exit(1);
 }
 
 require_once(BOOST_TASKS_DIR.'/webhook/webhook.php');