diff --git a/plugins/traction_innkeeper/traction_innkeeper/v1_0/connections/routes.py b/plugins/traction_innkeeper/traction_innkeeper/v1_0/connections/routes.py
index 0b44034a0..e3a1a41d4 100644
--- a/plugins/traction_innkeeper/traction_innkeeper/v1_0/connections/routes.py
+++ b/plugins/traction_innkeeper/traction_innkeeper/v1_0/connections/routes.py
@@ -24,6 +24,19 @@ async def connections_invitation(request: web.BaseRequest):
 
     profile = context.profile
     base_url = profile.settings.get("invite_base_url")
+
+    if not base_url:
+        base_url = profile.settings.get("default_endpoint")
+        if base_url:
+            LOGGER.debug(
+                "Using 'default_endpoint' as base URL for invitation because 'invite_base_url' is not configured."
+            )
+        else:
+            LOGGER.debug(
+                "Neither 'invite_base_url' nor 'default_endpoint' are configured. Invitation URL might be incomplete."
+            )
+            base_url = ""
+
     try:
         async with profile.session() as session:
             connection = await ConnRecord.retrieve_by_id(session, connection_id)
@@ -49,13 +62,18 @@ async def connections_invitation(request: web.BaseRequest):
         except BaseModelError as err:
             raise web.HTTPBadRequest(reason=err.roll_up) from err
 
-    invitation_url = invitation.to_url(base_url)
+    invitation_url = invitation.to_url(base_url) # Let's see what to_url produces
+
+    # Always prepend base_url if to_url returns only query params
+    if invitation_url.startswith("?"): # Check if to_url returned only query params
+        constructed_invitation_url = f"{base_url}{invitation_url}"
+    else:
+        constructed_invitation_url = invitation_url # Assume to_url worked correctly
+
     result = {
         "connection_id": connection_id,
         "invitation": invitation.serialize(),
-        "invitation_url": f"{invitation.endpoint}{invitation_url}"
-        if invitation_url.startswith("?")
-        else invitation_url,
+        "invitation_url": constructed_invitation_url,
     }
     if connection.alias:
         result["alias"] = connection.alias