Index: Drupal_Apache_Solr_Service.php
===================================================================
--- Drupal_Apache_Solr_Service.php	(revision 27077)
+++ Drupal_Apache_Solr_Service.php	(working copy)
@@ -228,6 +228,22 @@
   }
 
   protected function _makeHttpRequest($url, $method = 'GET', $headers = array(), $content = '', $timeout = FALSE) {
+    // This will no longer be needed after http://drupal.org/node/345591 is committed
+    static $responses = array(
+      0 => 'Request failed',
+      100 => 'Continue', 101 => 'Switching Protocols',
+      200 => 'OK', 201 => 'Created', 202 => 'Accepted', 203 => 'Non-Authoritative Information', 204 => 'No Content', 205 => 'Reset Content', 206 => 'Partial Content',
+      300 => 'Multiple Choices', 301 => 'Moved Permanently', 302 => 'Found', 303 => 'See Other', 304 => 'Not Modified', 305 => 'Use Proxy', 307 => 'Temporary Redirect',
+      400 => 'Bad Request', 401 => 'Unauthorized', 402 => 'Payment Required', 403 => 'Forbidden', 404 => 'Not Found', 405 => 'Method Not Allowed', 406 => 'Not Acceptable', 407 => 'Proxy Authentication Required', 408 => 'Request Time-out', 409 => 'Conflict', 410 => 'Gone', 411 => 'Length Required', 412 => 'Precondition Failed', 413 => 'Request Entity Too Large', 414 => 'Request-URI Too Large', 415 => 'Unsupported Media Type', 416 => 'Requested range not satisfiable', 417 => 'Expectation Failed',
+      500 => 'Internal Server Error', 501 => 'Not Implemented', 502 => 'Bad Gateway', 503 => 'Service Unavailable', 504 => 'Gateway Time-out', 505 => 'HTTP Version not supported'
+    );
+
+    // These response codes from solr will cause an exception to trigger a detailed watchdog entry
+    static $exception_for_responses = array(
+      400, 401, 402, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417,
+      500, 501, 502, 503, 504, 505,
+    );
+
     // Set a response timeout
     if ($timeout) {
       $default_socket_timeout = ini_set('default_socket_timeout', $timeout);
@@ -238,16 +254,6 @@
       ini_set('default_socket_timeout', $default_socket_timeout);
     }
 
-    // This will no longer be needed after http://drupal.org/node/345591 is committed
-    $responses = array(
-      0 => 'Request failed',
-      100 => 'Continue', 101 => 'Switching Protocols',
-      200 => 'OK', 201 => 'Created', 202 => 'Accepted', 203 => 'Non-Authoritative Information', 204 => 'No Content', 205 => 'Reset Content', 206 => 'Partial Content',
-      300 => 'Multiple Choices', 301 => 'Moved Permanently', 302 => 'Found', 303 => 'See Other', 304 => 'Not Modified', 305 => 'Use Proxy', 307 => 'Temporary Redirect',
-      400 => 'Bad Request', 401 => 'Unauthorized', 402 => 'Payment Required', 403 => 'Forbidden', 404 => 'Not Found', 405 => 'Method Not Allowed', 406 => 'Not Acceptable', 407 => 'Proxy Authentication Required', 408 => 'Request Time-out', 409 => 'Conflict', 410 => 'Gone', 411 => 'Length Required', 412 => 'Precondition Failed', 413 => 'Request Entity Too Large', 414 => 'Request-URI Too Large', 415 => 'Unsupported Media Type', 416 => 'Requested range not satisfiable', 417 => 'Expectation Failed',
-      500 => 'Internal Server Error', 501 => 'Not Implemented', 502 => 'Bad Gateway', 503 => 'Service Unavailable', 504 => 'Gateway Time-out', 505 => 'HTTP Version not supported'
-    );
-
     if (!isset($result->code) || $result->code < 0) {
       $result->code = 0;
     }
@@ -264,6 +270,11 @@
       $result->code = floor($result->code / 100) * 100;
     }
 
+    if (in_array($result->code, $exception_for_responses)) {
+      // hand over solr's exception details
+      throw new Exception('"' . $result->code . ' ' . $responses[$result->code] . '" Status: ' . $result->data);
+    }
+
     $protocol = "HTTP/1.1";
     $headers[] = "{$protocol} {$result->code} {$responses[$result->code]}";
     if (isset($result->headers)) {