Problem to solve
I am trying to use the GitLab Duo Agent Platform (custom agents), but every request fails.
What I am seeing:
When I try to use any custom agent I create, it immediately fails with the generic error:
There was an error processing your request in the Duo Agent Platform, please try again or contact support if the issue persists.
What I expect to see:
I expect the custom agent to execute its flow and provide a response.
Crucial Detail: The normal GitLab Duo Chat works perfectly fine. If I just message the default “Duo Agent” (not a custom agent), it answers my questions, explains code, etc. The error only happens with custom agents.
Most Important Detail: I am experiencing this identical failure on both my self-managed instance AND on my GitLab .com account.
Steps to reproduce
-
In any project, open the GitLab Duo Chat window in the Web UI.
-
click the
chat icon a top the screento list available agents. -
Select any custom-made agent (e.g.,
my_agent). -
Send any prompt.
-
Result: The agent immediately returns the “error processing your request” message.
-
(For comparison) Select the default “Duo Agent” from the list.
-
Send any prompt.
-
Result: The default agent works correctly and returns a valid answer.
Configuration
Self-Managed Instance
My self-managed instance configuration is all green:
-
I have applied an Ultimate license with an active Duo Enterprise trial.
-
I have manually assigned my user account a
Duo Enterpriseseat inAdmin Area > GitLab Duo. -
I am testing in a project that is inside a Group namespace.
-
The Admin Area > GitLab Duo > Health Check passes all probes 100% (Network, License, Token, and End-to-end).
Here is the part of the full (and successful) health check report:
JSON
[
{
"name": "license_probe",
"success": true,
"message": "Subscription can be synchronized.",
"details": {
...
"add_on_products": {
"duo_core": [ { "quantity": 50, ... "trial": false } ],
"duo_enterprise": [ { "quantity": 100, ... "trial": true } ]
}
}
},
{
"name": "host_probe",
"success": true,
"message": "customers.gitlab.com reachable."
},
{
"name": "host_probe",
"success": true,
"message": "cloud.gitlab.com reachable."
},
{
"name": "access_probe",
"success": true,
"message": "Subscription synchronized successfully."
},
{
"name": "token_probe",
"success": true,
"message": "Access credentials are valid."
},
{
"name": "end_to_end_probe",
"success": true,
"message": "Authentication with the AI gateway services succeeded."
}
]
IDE Configuration
This is the most important part: I am not using an IDE.
I am not using VS Code or a JetBrains IDE. I am trying to run the custom agents directly from the GitLab Web UI.
I have seen the troubleshooting docs that mention switching from gRPC to WebSocket in the IDE settings, but I cannot apply this fix because I am not using an IDE.
Versions
-
Self-managed
-
GitLab .com SaaS
Which GitLab Duo feature is involved:
GitLab Duo Agent Platform (Custom Agents)
Versions:
-
GitLab Self-Managed:
18.5.1-ee -
GitLab .com SaaS:
18.5(Latest) -
IDE:
N/A(Using the GitLab Web Interface)
(note: gitlab. com has space because not allowed to post links)