diff --git a/CHANGES.rst b/CHANGES.rst
index d690e47..ace2b6b 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -6,6 +6,8 @@ releases, see the file `HISTORY.txt` in this folder.
 
 5.1 (unreleased)
 ----------------
+- Catch ``ldap.UNAVAILABLE`` exception while connecting to an LDAP server.
+  AD Azure may return such an exception. Contributed by Gauthier Bastien.
 
 
 5.0 (2023-02-02)
diff --git a/src/Products/LDAPUserFolder/LDAPDelegate.py b/src/Products/LDAPUserFolder/LDAPDelegate.py
index 67f3c12..f359989 100644
--- a/src/Products/LDAPUserFolder/LDAPDelegate.py
+++ b/src/Products/LDAPUserFolder/LDAPDelegate.py
@@ -196,7 +196,7 @@ def connect(self, bind_dn='', bind_pwd=''):
             conn.search_s(self.u_base, self.BASE, '(objectClass=*)')
             return conn
         except (AttributeError, ldap.SERVER_DOWN, ldap.NO_SUCH_OBJECT,
-                ldap.TIMEOUT, ldap.INVALID_CREDENTIALS,
+                ldap.TIMEOUT, ldap.INVALID_CREDENTIALS, ldap.UNAVAILABLE,
                 ldap.UNWILLING_TO_PERFORM):
             pass
 
@@ -211,7 +211,8 @@ def connect(self, bind_dn='', bind_pwd=''):
                                         op_timeout=server['op_timeout'])
                 return newconn
             except (ldap.SERVER_DOWN, ldap.TIMEOUT,  # NOQA: F841
-                    ldap.INVALID_CREDENTIALS, ldap.UNWILLING_TO_PERFORM) as e:
+                    ldap.INVALID_CREDENTIALS, ldap.UNWILLING_TO_PERFORM,
+                    ldap.UNAVAILABLE) as e:
                 exc = e
 
         # If we get here it means either there are no servers defined or we