diff --git a/aprendizations/learnapp.py b/aprendizations/learnapp.py
index 51c4eda..db1037b 100644
--- a/aprendizations/learnapp.py
+++ b/aprendizations/learnapp.py
@@ -376,12 +376,7 @@ class LearnApp(object):
         for tref, attr in topics.items():
             logger.debug(f'       + {tref}')
             for d in attr.get('deps', []):
-                if d not in g.nodes():
-                    logger.error(f'Topic "{tref}" depends on "{d}" but it '
-                                 f'does not exist')
-                    raise LearnException()
-                else:
-                    g.add_edge(d, tref)
+                g.add_edge(d, tref)
 
             t = g.nodes[tref]  # get current topic node
             t['name'] = attr.get('name', tref)
@@ -409,14 +404,20 @@ class LearnApp(object):
 
             # load questions as list of dicts
             topicpath: str = path.join(g.graph['prefix'], tref)
-            fullpath: str = path.join(topicpath, t['file'])
+            try:
+                fullpath: str = path.join(topicpath, t['file'])
+            except Exception:
+                msg1 = f'Invalid topic "{tref}"'
+                msg2 = f'Check dependencies of {", ".join(g.successors(tref))}'
+                raise LearnException(f'{msg1}. {msg2}')
 
             logger.debug(f'  Loading {fullpath}')
-            # questions: List[QDict] = load_yaml(fullpath, default=[])
             try:
                 questions: List[QDict] = load_yaml(fullpath)
             except Exception:
-                raise LearnException(f'Failed to load "{fullpath}"')
+                msg = f'Failed to load "{fullpath}"'
+                logger.error(msg)
+                raise LearnException(msg)
 
             if not isinstance(questions, list):
                 msg = f'File "{fullpath}" must be a list of questions'
--
libgit2 0.21.2