Cannot install self-hosted GitLab integration

[dalnoki]

Environment

SaaS (https://sentry.io/)

Steps to Reproduce

The customer is attempting to connect a self-hosted GitLab instance to Sentry, but the process fails with the following messages:

Related errors in Sentry here here and here.

They

• enabled the necessary IP addresses
• tried using different browsers
• confirmed they have both owner/manager/admin permissions in Sentry and owner permissions in GitLab
• they have seen the 401 also in the Gitlab Access Logs
• they took the steps mentioned in this GH issue

Expected Result

integration should be installed successfully

Actual Result

the customer cannot complete the installation

Product Area

Settings - Integrations

Link

No response

DSN

No response

Version

No response

[getsantry]

Routing to @getsentry/product-owners-settings-integrations for triage ⏲️

[getsantry]

Auto-routing to @getsentry/product-owners-settings-integrations for triage ⏲️

[sentaur-athena]

Prioritizing this for the next rotation. Will get back to you in 2 weeks.

[cathteng]

How did the customer fill in the Gitlab integration installation form, and how did they set up the Sentry app in Gitlab? Is there a Zendesk ticket for this issue? This seems like an issue on their side if it works on non self-hosted Gitlab

[JTLMarcVoelker]

We are experiencing the same issue and were already referred from our Zendesk ticket (148353) to this issue. Unfortunately, the integration is not working for us either due to the same cause.
Here some Pictures