diff --git a/calendar/teachingdates/app.py b/calendar/teachingdates/app.py
index d306da6..b5ae874 100644
--- a/calendar/teachingdates/app.py
+++ b/calendar/teachingdates/app.py
@@ -3,9 +3,9 @@
 import pathlib
 import sys
 
-from teachingdates import PROG
 import teachingdates.calendars as calendars
 import teachingdates.config as configuration
+from teachingdates import PROG
 
 
 def run():
@@ -14,30 +14,42 @@
         print("{prog}: debug: args: {a}".format(prog=PROG, a=args))
 
     try:
-        config = configuration.Configuration(args)
+        dates_config = configuration.Configuration(args)
         if args.debug:
             print("{prog}: debug: period config: {c}".format(
-                prog=PROG, c=config.get_period_config()))
+                prog=PROG, c=dates_config.get_period_config()))
             print("{prog}: debug: paper config: {c}".format(
-                prog=PROG, c=config.get_paper_config()))
-        cal = calendars.TeachingCalendar(
-            config.year, config.period, config.paper,
-            config.get_period_config(), config.get_paper_config())
+                prog=PROG, c=dates_config.get_paper_config()))
+        cal = calendars.TeachingCalendar(dates_config.year,
+                                         dates_config.period,
+                                         dates_config.paper,
+                                         dates_config.get_period_config(),
+                                         dates_config.get_paper_config())
         print("Period = {p}".format(p=args.period))
         print(cal.calendar())
         print(cal.lecture_dates())
-    except configuration.LectureStyleError as e:
-        print("{prog}: error: 'lecture' style was requested but "
-            "{c} contains no papers for {t}.".format(
-                prog=PROG, c=args.config, t=args.period))
+
+    except configuration.ConfigurationError as e:
+        print("{prog}: error: failed to load configuration from "
+              "'{file}'.".format(prog=PROG, file=e))
+    except configuration.PaperKeyError as e:
+        print("{prog}: error: paper '{paper}' in '{file}' is missing "
+              "required key '{key}'.".format(prog=PROG,
+                                             paper=e.parent,
+                                             file=e.file,
+                                             key=e.key))
+    except configuration.PeriodKeyError as e:
+        print("{prog}: error: teaching period '{period}' in '{file}' is "
+              "missing required key '{key}'.".format(prog=PROG,
+                                                     period=e.parent,
+                                                     file=e.file,
+                                                     key=e.key))
     except configuration.PaperError as e:
-        print("{prog}: error: no entry in {c} for paper {p} ({t}).".format(
-            prog=PROG, c=args.config, p=args.paper, t=args.period))
+        print("{prog}: error: no entry for paper '{paper}' ({period}) in "
+              "'{file}.'".format(prog=PROG,
+                                 file=e,
+                                 paper=args.paper,
+                                 period=args.period))
     except configuration.PeriodError as e:
-        print("{prog}: error: no entry in {c} for teaching "
-            "period {p}.".format(
-                prog=PROG, c=args.config_file, p=args.period))
-    except KeyError as e:
-        print("{prog}: error: teaching period {p} in {c} is missing "
-            "required key {k}.".format(
-                prog=PROG, p=args.period, c=args.config, k=e))
+        print("{prog}: error: no entry for teaching period '{period}' in "
+              "'{file}'.".format(prog=PROG, file=e, period=args.period))