diff --git a/api/blueprints/mail/oauth_callback.py b/api/blueprints/mail/oauth_callback.py
index 092e0e0..8780935 100644
--- a/api/blueprints/mail/oauth_callback.py
+++ b/api/blueprints/mail/oauth_callback.py
@@ -283,14 +283,19 @@ async def mail_auth_callback(
     # ┣┫┏┓┏┓┏┫┃┏┓  ┃ ┏┓┃┃┣┓┏┓┏┃┏┏
     # ┛┗┗┻┛┗┗┻┗┗   ┗┛┗┻┗┗┗┛┗┻┗┛┗┛
 
-    if mail_client == "gmail": return await handle_gmail_callback()
-    # try:
-    #
-    #     if mail_client == "gmail": return await handle_gmail_callback()
-    #
-    # except Exception as exception:
-    #
-    #     pass
+    try:
+
+        if mail_client == "gmail": return await handle_gmail_callback()
+
+    # If something goes wrong:
+    except Exception as exception: return await render_template(
+        "/mail/oauth/oauth_failure_v2.html",
+        mail_client = mail_client.title(),
+        failure_hint = (
+            f"An internal server error occurred. "
+            f"Please use log-id '{g.log_id}' to check with the support team."
+        )
+    )
 
     # ┓┏     ┓┓    ┳      ┓• ┓  ┏┓┓•
     # ┣┫┏┓┏┓┏┫┃┏┓  ┃┏┓┓┏┏┓┃┓┏┫  ┃ ┃┓┏┓┏┓╋
diff --git a/models/data/core/auth_token.py b/models/data/core/auth_token.py
index ad5155b..22bc14b 100644
--- a/models/data/core/auth_token.py
+++ b/models/data/core/auth_token.py
@@ -152,7 +152,7 @@ class CoreAuthTokenModel(BaseModel):
 
     clientUserId: dict = Field(
         description = "how third-party client identifies the same user",
-        frozen = True
+        frozen = False
     )
 
     status: Literal["pending", "active", "disabled"] = Field(