# CRITICAL - UEFN session not start in Fortnite (map testing not possible !!!)

**URL:** <https://forums.unrealengine.com/t/critical-uefn-session-not-start-in-fortnite-map-testing-not-possible/2085218>\
**Category:** Issues and Bug Reporting\
**Tags:** testing, unreal-editor-for-fortnite, bug-report, fortnite\
**Created:** [October 24, 2024, 12:38pm UTC](https://forums.unrealengine.com/t/critical-uefn-session-not-start-in-fortnite-map-testing-not-possible/2085218 "2024-10-24T12:38:44Z")\
**Posts on this page:** 1\
**Showing post:** 13

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**Author:** ![Jimbohalo10](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/jimbohalo10/32/961440_2.png) [@Jimbohalo10](https://forums.unrealengine.com/u/Jimbohalo10)\
**Post date:** [October 25, 2024, 1:56am UTC](https://forums.unrealengine.com/t/critical-uefn-session-not-start-in-fortnite-map-testing-not-possible/2085218/13 "2024-10-25T01:56:39Z")

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hi @Karo-Bube , @Hardcawcanary ,

> In this case I launched game start from UEFN and Fortnite ends with “log in failure”

Often login failures can be cured by running as an administrator .  
See the last picture in the post

[[Solved] How to fix Fatal Errors in UEFN related to Graphic Cards and Shaders and Derived Data problems ](https://forums.unrealengine.com/t/solved-how-to-fix-fatal-errors-in-uefn-related-to-graphic-cards-and-shaders-and-derived-data-problems/2080832)

Then a good idea is to verify your installation

[verify UEFN/Fortnite installation](https://forums.unrealengine.com/t/urc-exe-and-urc-dll-get-flagged-as-malware-from-microsoft-defender/1802519/5)

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