Index: /branches/1.0/test/functional/validationTest.php
===================================================================
--- /branches/1.0/test/functional/validationTest.php (revision 3168)
+++ /branches/1.0/test/functional/validationTest.php (revision 8922)
@@ -138,2 +138,41 @@
   checkResponseElement('body ul[class="errors"] li[class="input4"]', 'Required')
 ;
+
+// check that /validation/index and /validation/Index both uses the index.yml validation file (see #1617)
+// those tests are only relevant on machines where filesystems are case sensitive.
+$b->
+  post('/validation/index')->
+  isStatusCode(200)->
+  isRequestParameter('module', 'validation')->
+  isRequestParameter('action', 'index')->
+  isResponseHeader('X-Validated', 'ko')
+;
+
+$b->
+  post('/validation/Index')->
+  isStatusCode(200)->
+  isRequestParameter('module', 'validation')->
+  isRequestParameter('action', 'Index')->
+  isResponseHeader('X-Validated', 'ko')
+;
+
+$b->
+  post('/validation/INdex')->
+  isStatusCode(404)
+;
+
+$b->
+  post('/validation/index2')->
+  isStatusCode(200)->
+  isRequestParameter('module', 'validation')->
+  isRequestParameter('action', 'index2')->
+  isResponseHeader('X-Validated', 'ko')
+;
+
+$b->
+  post('/validation/Index2')->
+  isStatusCode(200)->
+  isRequestParameter('module', 'validation')->
+  isRequestParameter('action', 'Index2')->
+  isResponseHeader('X-Validated', 'ko')
+;
Index: /branches/1.0/test/functional/fixtures/project/apps/frontend/modules/validation/actions/actions.class.php
===================================================================
--- /branches/1.0/test/functional/fixtures/project/apps/frontend/modules/validation/actions/actions.class.php (revision 3168)
+++ /branches/1.0/test/functional/fixtures/project/apps/frontend/modules/validation/actions/actions.class.php (revision 8922)
@@ -13,8 +13,29 @@
   public function executeIndex()
   {
+    if (sfWebRequest::POST == $this->getRequest()->getMethod())
+    {
+      $this->getResponse()->setHttpHeader('X-Validated', 'ok');
+    }
   }
 
   public function handleErrorIndex()
   {
+    $this->getResponse()->setHttpHeader('X-Validated', 'ko');
+
+    return sfView::SUCCESS;
+  }
+
+  public function executeIndex2()
+  {
+    if (sfWebRequest::POST == $this->getRequest()->getMethod())
+    {
+      $this->getResponse()->setHttpHeader('X-Validated', 'ok');
+    }
+  }
+
+  public function handleErrorIndex2()
+  {
+    $this->getResponse()->setHttpHeader('X-Validated', 'ko');
+
     return sfView::SUCCESS;
   }
Index: /branches/1.0/test/functional/fixtures/project/apps/frontend/modules/validation/validate/Index2.yml
===================================================================
--- /branches/1.0/test/functional/fixtures/project/apps/frontend/modules/validation/validate/Index2.yml (revision 8922)
+++ /branches/1.0/test/functional/fixtures/project/apps/frontend/modules/validation/validate/Index2.yml (revision 8922)
@@ -0,0 +1,22 @@
+methods:
+  post:
+    - fake
+    - id
+    - "article[title]"
+    - "article[body]"
+
+fillin:
+  enabled:  on
+
+names:
+  fake:
+    required: yes
+
+  id:
+    required: yes
+
+  "article[title]":
+    required: yes
+
+  "article[body]":
+    required: yes
Index: /branches/1.0/lib/filter/sfExecutionFilter.class.php
===================================================================
--- /branches/1.0/lib/filter/sfExecutionFilter.class.php (revision 7791)
+++ /branches/1.0/lib/filter/sfExecutionFilter.class.php (revision 8922)
@@ -72,10 +72,24 @@
         $validated = true;
 
+        // the case of the first letter of the action is insignificant
         // get the current action validation configuration
-        $validationConfig = $moduleName.'/'.sfConfig::get('sf_app_module_validate_dir_name').'/'.$actionName.'.yml';
+        $validationConfigWithFirstLetterLower = $moduleName.'/'.sfConfig::get('sf_app_module_validate_dir_name').'/'.strtolower(substr($actionName, 0, 1)).substr($actionName, 1).'.yml';
+        $validationConfigWithFirstLetterUpper = $moduleName.'/'.sfConfig::get('sf_app_module_validate_dir_name').'/'.ucfirst($actionName).'.yml';
+
+        // determine $validateFile by testing both the uppercase and lowercase
+        // types of validation configurations.
+        $validateFile = null;
+        if (!is_null($testValidateFile = sfConfigCache::getInstance()->checkConfig(sfConfig::get('sf_app_module_dir_name').'/'.$validationConfigWithFirstLetterLower, true)))
+        {
+          $validateFile = $testValidateFile;
+        }
+        else if (!is_null($testValidateFile = sfConfigCache::getInstance()->checkConfig(sfConfig::get('sf_app_module_dir_name').'/'.$validationConfigWithFirstLetterUpper, true)))
+        {
+          $validateFile = $testValidateFile;
+        }
 
         // load validation configuration
         // do NOT use require_once
-        if (null !== $validateFile = sfConfigCache::getInstance()->checkConfig(sfConfig::get('sf_app_module_dir_name').'/'.$validationConfig, true))
+        if (!is_null($validateFile))
         {
           // create validator manager