diff --git a/cps/admin.py b/cps/admin.py
index 86e59317..bfcb9604 100755
--- a/cps/admin.py
+++ b/cps/admin.py
@@ -1631,7 +1631,10 @@ def import_ldap_users():
 
     imported = 0
     for username in new_users:
-        user = username.decode('utf-8')
+        if isinstance(username, bytes):
+            user = username.decode('utf-8')
+        else:
+            user = username
         if '=' in user:
             # if member object field is empty take user object as filter
             if config.config_ldap_member_user_object:
diff --git a/optional-requirements.txt b/optional-requirements.txt
index f4f0d169..4b34aef2 100644
--- a/optional-requirements.txt
+++ b/optional-requirements.txt
@@ -5,8 +5,8 @@ greenlet>=0.4.17,<3.1.0
 httplib2>=0.9.2,<0.23.0
 oauth2client>=4.0.0,<4.1.4
 uritemplate>=3.0.0,<4.2.0
-pyasn1-modules>=0.0.8,<0.4.0
-pyasn1>=0.1.9,<0.6.0
+pyasn1-modules>=0.0.8,<0.5.0
+pyasn1>=0.1.9,<0.7.0
 PyDrive2>=1.3.1,<1.20.0
 PyYAML>=3.12,<6.1
 rsa>=3.4.2,<4.10.0
@@ -21,18 +21,18 @@ python-Levenshtein>=0.12.0,<0.26.0
 
 # ldap login
 python-ldap>=3.0.0,<3.5.0
-Flask-SimpleLDAP>=1.4.0,<1.5.0
+Flask-SimpleLDAP>=1.4.0,<2.1.0
 
 # oauth
 Flask-Dance>=2.0.0,<7.1.0
 SQLAlchemy-Utils>=0.33.5,<0.42.0
 
 # metadata extraction
-rarfile>=3.2,<4.2
+rarfile>=3.2,<5.0
 scholarly>=1.2.0,<1.8
 markdown2>=2.0.0,<2.5.0
 html2text>=2020.1.16,<2024.2.26
-python-dateutil>=2.1,<2.9.0
+python-dateutil>=2.1,<2.10.0
 beautifulsoup4>=4.0.1,<4.13.0
 faust-cchardet>=2.1.18,<2.1.20
 py7zr>=0.15.0,<0.21.0
@@ -42,4 +42,4 @@ natsort>=2.2.0,<8.5.0
 comicapi>=2.2.0,<3.3.0
 
 # Kobo integration
-jsonschema>=3.2.0,<4.22.0
+jsonschema>=3.2.0,<4.23.0