# Errors "Failed to login - null" or "Failed to login - invalid session" when joining a server

## Issue Description

These errors mostly happen when there is a Microsoft account authentication issue on your launcher, whether it is Technic or CurseForge.

<table border="0" id="bkmrk-" style="border-collapse: collapse; width: 100%; border-style: hidden;"><tbody><tr><td style="padding: 4px; text-align: center; width: 50%;">[![Authentication error example 1](https://siriusmc-bookstack.s3.eu-west-1.amazonaws.com/uploads/images/gallery/2024-01/scaled-1680-/DlmnjQ2HxQdVsKMn-image.png)](https://siriusmc-bookstack.s3.eu-west-1.amazonaws.com/uploads/images/gallery/2024-01/DlmnjQ2HxQdVsKMn-image.png)</td><td style="padding: 4px; text-align: center; width: 50%;">[![Authentication error example 2](https://siriusmc-bookstack.s3.eu-west-1.amazonaws.com/uploads/images/gallery/2024-01/WtZSfmsfgxFRFs1w-image.png)](https://siriusmc-bookstack.s3.eu-west-1.amazonaws.com/uploads/images/gallery/2024-01/WtZSfmsfgxFRFs1w-image.png)</td></tr></tbody></table>

## Solution(s)

1\. Closing the game and launcher completely, logging out from the launcher, and relogging back in are the most common fixes.

2\. If that still doesn't work, you can navigate to **%appdata%/roaming/.technic** and delete the **oauth** folder.

If this still doesn't resolve the issue, you can open a support ticket on our [Discord](https://discord.gg/SiriusMC) server.