"Error connecting to n8n Could not connect to server" after upgrading to 1.109.1

TL;DR

For "TypeError: can't access property "ldap", options.config is undefined": i updated my self-hosted n8n to 1.109.1 and now the web UI shows a red banner: "Error connecting to n8n Could not connect to server.

TypeError: can't access property "ldap", options.config is undefined

Steps

1. I updated my self-hosted n8n to 1.109.1 and now the web UI shows a red banner: "Error connecting to n8n Could not connect to server. Refresh to try again." The backend container looks healthy. Downgrading to 1.108 makes it work again. I run n8n in Docker behind a plain setup, no SSO. What broke?
2. This was a real regression in the 1.109-1.121 range, not your config. From n8n 1.120 on, the new SSO initialization runs even when you do not use SSO, and if the SSO config vars do not exist in your setup the frontend crashes during init with TypeError: can't access property "ldap", options.config is undefined, which surfaces as the red "Error connecting to n8n" banner. Two verified fixes: update to 1.121.2 or the next docker tag (users confirmed the pre-release resolves it with no config changes), or if you want to stay on your version, explicitly disable the SSO features you are not using by adding these to your environment: N8NSSOSAMLENABLED=false, N8NSSOOIDCENABLED=false, N8NSSOLDAP_ENABLED=false, then restart the container. You can confirm the diagnosis before touching anything by opening the browser console (F12) and looking for the ldap TypeError.

When to use

You are seeing this: Refresh to try again." The backend container looks healthy. Use this skill when you run into ""Error connecting to n8n Could not connect to server" after upgrading to 1.109.1".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: 1.109.1, 1.109-1.121, 1.121.2. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Sources

• https://github.com/n8n-io/n8n/issues/19151

Someone asked: I updated my self-hosted n8n to 1.109.1 and now the web UI shows a red banner: "Error connecting to n8n Could not connect to server. Refresh to try again." The backend container looks healthy. Downgrading to 1.108 makes it work again. I run n8n in Docker behind a plain setup, no SSO. What broke? The verified resolution: This was a real regression in the 1.109-1.121 range, not your config. From n8n 1.120 on, the new SSO initialization runs even when you do not use SSO, and if the SSO config vars do not exist in your setup the frontend crashes during init with TypeError: can't access property "ldap", options.config is undefined, which surfaces as the red "Error connecting to n8n" banner. Two verified fixes: update to 1.121.2 or the next docker tag (users confirmed the pre-release resolves it with no config changes), or if you want to stay on your version, explicitly disable the SSO features you are not using by adding these to your environment: N8NSSOSAMLENABLED=false, N8NSSOOIDCENABLED=false, N8NSSOLDAPENABLED=false, then restart the container. You can confirm the diagnosis before touching anything by opening the browser console (F12) and looking for the ldap TypeError. Thread: https://vectle.com/threads/thrpVmmsS24cDngVkQEFDxcJg