diff --git a/seminar/migrations/0001_squashed_0067_auto_20190814_0805.py b/seminar/migrations/0001_squashed_0067_auto_20190814_0805.py
index 5eb3e452..f9a8b5eb 100644
--- a/seminar/migrations/0001_squashed_0067_auto_20190814_0805.py
+++ b/seminar/migrations/0001_squashed_0067_auto_20190814_0805.py
@@ -877,6 +877,7 @@ class Migration(migrations.Migration):
         ),
         migrations.RunSQL(
             sql='update seminar_rocniky set rocnik_n = cast (rocnik as integer)',
+            reverse_sql='update seminar_rocniky set rocnik_n = cast (rocnik as nvarchar(16))',
         ),
         migrations.RemoveField(
             model_name='rocnik',
@@ -1733,15 +1734,19 @@ class Migration(migrations.Migration):
         # migr 0052
         migrations.RunPython(
            spoj_k_organizatorum_osoby,
+        	reverse_code=migrations.RunPython.noop,
         ),
         migrations.RunPython(
             fix_problem,
+            reverse_code=migrations.RunPython.noop,
         ),
         migrations.RunPython(
             fix_pohadka,
+            reverse_code=migrations.RunPython.noop,
         ),
         migrations.RunPython(
             fix_novinka,
+            reverse_code=migrations.RunPython.noop,
         ),
 
         # migr 0053
@@ -1795,25 +1800,31 @@ class Migration(migrations.Migration):
         # migr 0056
         migrations.RunPython(
             generuj_RocnikNody_a_CisloNody,
+            reverse_code=migrations.RunPython.noop,
         ),
 
         # migr 0057
         migrations.RunPython(
             reseni_to_Reseni,
+            reverse_code=migrations.RunPython.noop,
         ),
 
         # migr 0058
         migrations.RunPython(
             uloha_to_Uloha,
+            reverse_code=migrations.RunPython.noop,
         ),
         migrations.RunPython(
             tema_to_Tema,
+            reverse_code=migrations.RunPython.noop,
         ),
         migrations.RunPython(
             clanek_to_Clanek,
+            reverse_code=migrations.RunPython.noop,
         ),
         migrations.RunPython(
             konfery_rucne,
+            reverse_code=migrations.RunPython.noop,
         ),
 
         # migr "fix 0058"
@@ -1825,11 +1836,13 @@ class Migration(migrations.Migration):
         # migr 0059
         migrations.RunPython(
             vytvor_pohadkanode,
+            reverse_code=migrations.RunPython.noop,
         ),
 
         # migr 0060
         migrations.RunPython(
             pokacej_les,
+            reverse_code=migrations.RunPython.noop,
         ),
 
         migrations.RemoveField(
diff --git a/seminar/migrations/0019_rocnik_ciselne.py b/seminar/migrations/0019_rocnik_ciselne.py
index 42308b2f..da9591aa 100644
--- a/seminar/migrations/0019_rocnik_ciselne.py
+++ b/seminar/migrations/0019_rocnik_ciselne.py
@@ -18,7 +18,8 @@ class Migration(migrations.Migration):
             preserve_default=False,
         ),
         migrations.RunSQL(
-            sql="update seminar_rocniky set rocnik_n = cast (rocnik as integer)"
+            sql="update seminar_rocniky set rocnik_n = cast (rocnik as integer)",
+            reverse_sql='update seminar_rocniky set rocnik_n = cast (rocnik as nvarchar(16))',
         ),
         migrations.RemoveField(
             model_name='rocnik',
diff --git a/seminar/migrations/0052_user_to_organizator.py b/seminar/migrations/0052_user_to_organizator.py
index d52e29ca..db3827ce 100644
--- a/seminar/migrations/0052_user_to_organizator.py
+++ b/seminar/migrations/0052_user_to_organizator.py
@@ -75,8 +75,8 @@ class Migration(migrations.Migration):
 	]
 
 	operations = [
-		migrations.RunPython(spoj_k_organizatorum_osoby),
-		migrations.RunPython(fix_problem),
-		migrations.RunPython(fix_pohadka),
-		migrations.RunPython(fix_novinka),
+		migrations.RunPython(spoj_k_organizatorum_osoby, migrations.RunPython.noop),
+		migrations.RunPython(fix_problem, migrations.RunPython.noop),
+		migrations.RunPython(fix_pohadka, migrations.RunPython.noop),
+		migrations.RunPython(fix_novinka, migrations.RunPython.noop),
 	]
diff --git a/seminar/migrations/0056_vrcholy_pro_rocniky_a_cisla.py b/seminar/migrations/0056_vrcholy_pro_rocniky_a_cisla.py
index 024400a4..56146261 100644
--- a/seminar/migrations/0056_vrcholy_pro_rocniky_a_cisla.py
+++ b/seminar/migrations/0056_vrcholy_pro_rocniky_a_cisla.py
@@ -43,5 +43,5 @@ class Migration(migrations.Migration):
 	]
 
 	operations = [
-		migrations.RunPython(generuj_RocnikNody_a_CisloNody),
+		migrations.RunPython(generuj_RocnikNody_a_CisloNody, migrations.RunPython.noop),
 	]
diff --git a/seminar/migrations/0057_reseni_to_reseni_hodnoceni.py b/seminar/migrations/0057_reseni_to_reseni_hodnoceni.py
index b3f0405b..a11d99ae 100644
--- a/seminar/migrations/0057_reseni_to_reseni_hodnoceni.py
+++ b/seminar/migrations/0057_reseni_to_reseni_hodnoceni.py
@@ -30,5 +30,5 @@ class Migration(migrations.Migration):
 	]
 
 	operations = [
-		migrations.RunPython(reseni_to_Reseni)		
+		migrations.RunPython(reseni_to_Reseni, migrations.RunPython.noop)
 	]
diff --git a/seminar/migrations/0058_problem_to_uloha_tema_clanek.py b/seminar/migrations/0058_problem_to_uloha_tema_clanek.py
index 333f5453..7d651edb 100644
--- a/seminar/migrations/0058_problem_to_uloha_tema_clanek.py
+++ b/seminar/migrations/0058_problem_to_uloha_tema_clanek.py
@@ -154,8 +154,8 @@ class Migration(migrations.Migration):
 
 	operations = [
 		# ashes to Ashes, dust to Dust....
-		migrations.RunPython(uloha_to_Uloha),
-		migrations.RunPython(tema_to_Tema),
-		migrations.RunPython(clanek_to_Clanek),
-		migrations.RunPython(konfery_rucne),
+		migrations.RunPython(uloha_to_Uloha, migrations.RunPython.noop),
+		migrations.RunPython(tema_to_Tema, migrations.RunPython.noop),
+		migrations.RunPython(clanek_to_Clanek, migrations.RunPython.noop),
+		migrations.RunPython(konfery_rucne, migrations.RunPython.noop),
 	]
diff --git a/seminar/migrations/0059_vytvorit_pohadkanode.py b/seminar/migrations/0059_vytvorit_pohadkanode.py
index d0edd677..2a78c7ee 100644
--- a/seminar/migrations/0059_vytvorit_pohadkanode.py
+++ b/seminar/migrations/0059_vytvorit_pohadkanode.py
@@ -25,5 +25,5 @@ class Migration(migrations.Migration):
 	]
 
 	operations = [
-		migrations.RunPython(vytvor_pohadkanode),
+		migrations.RunPython(vytvor_pohadkanode, migrations.RunPython.noop),
 	]
diff --git a/seminar/migrations/0060_spoj_stromy.py b/seminar/migrations/0060_spoj_stromy.py
index a94caf48..c02b8d12 100644
--- a/seminar/migrations/0060_spoj_stromy.py
+++ b/seminar/migrations/0060_spoj_stromy.py
@@ -108,5 +108,5 @@ class Migration(migrations.Migration):
 	]
 
 	operations = [
-		migrations.RunPython(pokacej_les),
+		migrations.RunPython(pokacej_les, migrations.RunPython.noop),
 	]
diff --git a/seminar/migrations/0068_treenode_nazev.py b/seminar/migrations/0068_treenode_nazev.py
index bead85d3..c0024c8d 100644
--- a/seminar/migrations/0068_treenode_nazev.py
+++ b/seminar/migrations/0068_treenode_nazev.py
@@ -103,5 +103,5 @@ class Migration(migrations.Migration):
             name='nazev',
             field=models.TextField(help_text='Tento název se zobrazuje v nabídkách pro výběr vhodného TreeNode', null=True, verbose_name='název tohoto node'),
         ),
-        migrations.RunPython(fix_all_names),
+        migrations.RunPython(fix_all_names, migrations.RunPython.noop),
     ]
diff --git a/seminar/migrations/0080_zruseni_claneknode_a_konferanode.py b/seminar/migrations/0080_zruseni_claneknode_a_konferanode.py
index 13d083f9..34c22249 100644
--- a/seminar/migrations/0080_zruseni_claneknode_a_konferanode.py
+++ b/seminar/migrations/0080_zruseni_claneknode_a_konferanode.py
@@ -65,6 +65,9 @@ class Migration(migrations.Migration):
             model_name='reseni',
             name='text_zkraceny',
         ),
+        migrations.DeleteModel(  # nejdříve musím smazat objekt ukazující na konferu,
+            name='KonferaNode',  # pak až změnit klíč konferám (viz další operace)
+        ),
         migrations.AddField(
             model_name='konfera',
             name='problem_ptr',
@@ -95,9 +98,6 @@ class Migration(migrations.Migration):
         migrations.DeleteModel(
             name='ClanekNode',
         ),
-        migrations.DeleteModel(
-            name='KonferaNode',
-        ),
         migrations.CreateModel(
             name='Konfery_Ucastnici',
             fields=[