---
title: "Troubleshooting - GrantID"
description: "Diagnosing problems on an on-premises GrantID, such as the nginx 502 Bad Gateway on the authorize callback during authentication, and its fix."
canonical: "https://docs.lacunasoftware.com/en-us/articles/grant-id/on-premises/troubleshoot"
locale: "en"
product: "GrantID"
last_updated: "2026-07-14"
---

# Troubleshooting - GrantID

Here you can find information that may help you to diagnose problems on your [on-premises](https://docs.lacunasoftware.com/en-us/articles/grant-id/on-premises) instance of [GrantID](https://docs.lacunasoftware.com/en-us/articles/grant-id).

## Nginx returns *502 Bad Gatewway* when accessing */connect/authorize/callback* during authentication flow

On scenarios on which an nginx reverse proxy is used, a *502 Bad Gatewway* error may occur during the authentication flow, more specifically when
*/connect/authorize/callback* is called:

> **Note**
>
> This issue can affect instances on AWS and also on Kubernetes when using an nginx-based ingress

![Error 502 on auth callback](https://docs.lacunasoftware.com/images/grant-id/error-502-on-auth-callback.png)

To fix this, set the following settings on your nginx configuration file:

```nginx
proxy-buffer-size: 256k
proxy-buffering: 'on'
proxy-buffers: 4 "512k"
```

For instance:

```nginx
server {

    ...

    location / {
        proxy_pass         ...
        ...
        proxy-buffer-size: 256k
        proxy-buffering: 'on'
        proxy-buffers: 4 "512k"
    }
}
```

On Kubernetes, these are usually set on the ingress controller's config map:

![Proxy buffer configuration on Kubernetes](https://docs.lacunasoftware.com/images/grant-id/kubernetes-proxy-buffer-config.png)

## See also

* [GrantID Settings](https://docs.lacunasoftware.com/en-us/articles/grant-id/on-premises/settings)
* [Serilog Configuration](https://docs.lacunasoftware.com/en-us/articles/grant-id/on-premises/serilog)