possible fix to #1209

Author: alejcas

O365/connection.py

@@ -880,11 +880,14 @@ def refresh_token(self) -> bool:
             username=self.username, remove_reserved=True
         )
 
-        # call the refresh!
-        result = self.msal_client.acquire_token_silent_with_error(
-            scopes=scopes,
-            account=self.msal_client.get_accounts(username=self.username)[0],
-        )
+        if self.auth_flow_type == "credentials":
+            result = self.msal_client.acquire_token_for_client(scopes=scopes)
+        else:
+            # call the refresh!
+            result = self.msal_client.acquire_token_silent_with_error(
+                scopes=scopes,
+                account=self.msal_client.get_accounts(username=self.username)[0],
+            )
         if result is None:
             raise RuntimeError("There is no refresh token to refresh")
         elif "error" in result: