diff --git a/xmlsitemap.install b/xmlsitemap.install
index 200ab69..169bd96 100644
--- a/xmlsitemap.install
+++ b/xmlsitemap.install
@@ -111,7 +111,7 @@ function xmlsitemap_requirements($phase) {
     $generated_ago = REQUEST_TIME - $generated_last;
     $requirements['xmlsitemap_generated'] = array(
       'title' => $t('XML sitemap'),
-      'value' => $generated_last ? $t('Last generated on !date (!interval ago).', array('!date' => format_date($generated_last, 'small'), '!interval' => format_interval($generated_ago))) : $t('Cached files have not been generated yet.'),
+      'value' => $generated_last ? $t('Last attempted generation on !date (!interval ago).', array('!date' => format_date($generated_last, 'small'), '!interval' => format_interval($generated_ago))) : $t('Cached files have not been generated yet.'),
       'severity' => REQUIREMENT_OK,
     );
     if (variable_get('xmlsitemap_rebuild_needed', FALSE) && _xmlsitemap_rebuild_form_access()) {
@@ -119,7 +119,11 @@ function xmlsitemap_requirements($phase) {
       $requirements['xmlsitemap_generated']['description'] = $t('The XML sitemap data is out of sync and needs to be <a href="@link-rebuild">completely rebuilt<a>.', array('@link-rebuild' => url('admin/config/search/xmlsitemap/rebuild')));
     }
     elseif (variable_get('xmlsitemap_regenerate_needed', FALSE)) {
-      if ($generated_ago >= variable_get('cron_threshold_error', 1209600)) {
+      if ($max_filesize == 0) {
+        // A maximum sitemap file size of 0 indicates an error in generation.
+        $requirements['xmlsitemap_generated']['severity'] = REQUIREMENT_ERROR;
+      }
+      elseif ($generated_ago >= variable_get('cron_threshold_error', 1209600)) {
         $requirements['xmlsitemap_generated']['severity'] = REQUIREMENT_ERROR;
       }
       elseif ($generated_ago >= variable_get('cron_threshold_warning', 172800)) {
diff --git a/xmlsitemap.xmlsitemap.inc b/xmlsitemap.xmlsitemap.inc
index e3103ae..46ab406 100644
--- a/xmlsitemap.xmlsitemap.inc
+++ b/xmlsitemap.xmlsitemap.inc
@@ -5,6 +5,10 @@
  * XML sitemap integration functions for xmlsitemap.module.
  */
 
+class XMLSitemapException extends Exception {}
+
+class XMLSitemapGenerationException extends XMLSitemapException {}
+
 /**
  * Extended class for writing XML sitemap files.
  */
@@ -33,9 +37,9 @@ class XMLSitemapWriter extends XMLWriter {
   }
 
   public function openUri($uri) {
-    $return = parent::openUri($uri);
+    $return = parent::openUri(drupal_realpath($uri));
     if (!$return) {
-      trigger_error(t('Could not open file @file for writing.', array('@file' => $uri)));
+      throw new XMLSitemapGenerationException(t('Could not open file @file for writing.', array('@file' => $uri)));
     }
     return $return;
   }
@@ -150,8 +154,7 @@ class XMLSitemapWriter extends XMLWriter {
     $return = parent::endDocument();
 
     if (!$this->getStatus()) {
-      trigger_error(t('Unknown error occurred while writing to file @file.', array('@file' => $this->uri)));
-      return FALSE;
+      throw new XMLSitemapGenerationException(t('Unknown error occurred while writing to file @file.', array('@file' => $this->uri)));
     }
 
     //if (xmlsitemap_var('gz')) {