diff --git a/app.py b/app.py
index 71da579..7ffe13d 100644
--- a/app.py
+++ b/app.py
@@ -51,17 +51,13 @@ class App(object):
 
     # ------------------------------------------------------------------------
     def __init__(self, conf={}):
-        logger.info('Starting application')
+        logger.info('Starting application.')
         self.online = dict()    # {uid: {'student':{...}, 'test': {...}}, ...}
         self.allowed = set([])  # '0' is hardcoded to allowed elsewhere
 
-        # build test configuration dictionary
-        testconf = {}
-        if conf['filename']:
-            logger.info(f'Loading test configuration "{conf["filename"]}".')
-            testconf.update(load_yaml(conf['filename']))
-
-        testconf.update(conf)  # configuration overrides
+        logger.info(f'Loading test configuration "{conf["filename"]}".')
+        testconf = load_yaml(conf['filename'], default={})
+        testconf.update(conf)  # configuration overrides from command line
 
         # start test factory
         try:
diff --git a/serve.py b/serve.py
index 6e86bb0..6921ed1 100755
--- a/serve.py
+++ b/serve.py
@@ -17,7 +17,7 @@ import json
 import tornado.ioloop
 import tornado.web
 import tornado.httpserver
-from tornado import template, gen
+from tornado import template, gen, websocket
 import yaml
 
 # this project
@@ -48,6 +48,7 @@ class WebApplication(tornado.web.Application):
             (r'/review',        ReviewHandler),
             (r'/admin',         AdminHandler),
             (r'/file',          FileHandler),
+            # (r'/ws',            SocketHandler),
             (r'/',              RootHandler), # TODO multiple tests
         ]
 
@@ -138,6 +139,7 @@ class FileHandler(BaseHandler):
         uid = self.current_user
         ref = self.get_query_argument('ref', None)
         image = self.get_query_argument('image', None)
+        content_type, encoding = mimetypes.guess_type(image)
 
         if uid != '0':
             t = self.testapp.get_student_test(uid)
@@ -149,6 +151,7 @@ class FileHandler(BaseHandler):
             raise tornado.web.HTTPError(404)  # Not Found
 
         for q in t['questions']:
+            # search for the question that contains the image
             if q['ref'] == ref:
                 filepath = path.join(q['path'], 'public', image)
 
@@ -159,11 +162,11 @@ class FileHandler(BaseHandler):
                 except PermissionError:
                     logging.error(f'No permission: {filepath}')
                 else:
-                    content_type = mimetypes.guess_type(image)
-                    self.set_header("Content-Type", content_type[0])
-                    with f:
-                        self.write(f.read())
-                        await self.flush()
+                    data = f.read()
+                    f.close()
+                    self.set_header("Content-Type", content_type)
+                    self.write(data)
+                    await self.flush()
 
 
 
@@ -416,6 +419,8 @@ def main():
     except:
         print('An error ocurred while setting up the logging system.')
         sys.exit(1)
+
+    # start logging
     logging.info('===============================================')
 
     # --- start application
diff --git a/test.py b/test.py
index 08930ab..0a8ab6f 100644
--- a/test.py
+++ b/test.py
@@ -44,21 +44,21 @@ class TestFactory(dict):
         self.question_factory.load_files(files=self['files'], questions_dir=self['questions_dir'])
 
         # check if all questions exist ('ref' keys are correct?)
-        errors_found = False
+        errors_found = []
         for q in self['questions']:
             for r in q['ref']:
-                logger.info(f'Checking question "{r}".')
+                logger.info(f'  Checking "{r}".')
                 try:
                     self.question_factory.generate(r)
                 except:
                     logger.critical(f'Can\'t generate question "{r}".')
-                    errors_found = True
+                    errors_found.append(r)
 
         if errors_found:
-            logger.critical('Errors found while generating questions.')
+            logger.critical(f'{errors_found} errors found generating questions.')
             raise TestFactoryException()
-
-        logger.info(f'Test factory ready for "{self["ref"]}".')
+        else:
+            logger.info(f'No errors found. Test factory ready for "{self["ref"]}".')
 
 
     # -----------------------------------------------------------------------
--
libgit2 0.21.2