Everest crashes during launching due to CoreCLR 10.0.2 not supported | Mt. Celeste Climbing Association | Page 1

calm hill Jan 24, 2026, 8:10 AM

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i have tried launching game directly from steam and from olympus launcher. but after the splash screen it just popped out a errorLog.txt. it's System.PlatformNotSupportedException: CoreCLR version 10.0.2 is not supported.
the most related event maybe yesterday i installed vs2026.
what i have tried:

reinstall olympus
reinstall everest ver. 6129, 6131, 6146(btw originally my everest version is 6088)
one of my friend says his pc has used dotnet10 for a long time and havnt come into an issue with everest (6129) so i guess it's not the dotnet env problem?
also the dotnet installation is bind with my vs2026, which means i have to remove dotnet10 from my dev env to make my everest work😭

📎 errorLog.txt

plush dawn Jan 24, 2026, 1:33 PM

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could it be an outdated mod?

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but yeah that's a weird error

rapid pulsar Jan 24, 2026, 11:34 PM

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calm hill i have tried launching game directly from steam and from olympus launcher. but a...

the version of monomod everest uses does not support .NET 10

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i'm guessing piton is trying to run celeste with the .net 10 runtime

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@lyric pine is this what could be happening

lyric pine Jan 24, 2026, 11:57 PM

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are you using any custom steam launch args?

calm hill Jan 25, 2026, 12:05 PM

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lyric pine are you using any custom steam launch args?

no

lyric pine Jan 25, 2026, 12:19 PM

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send the piton-runtime.yaml file in your game files, and send the latest log.txt please

lethal crypt Jan 25, 2026, 12:53 PM

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and Celeste.runtimeconfig.json i guess

rapid pulsar Jan 25, 2026, 4:20 PM

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@calm hill

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i can reproduce this if i set the runtimeconfig.json to this, but i don't see how that would be possible to do accidentally

calm hill Jan 25, 2026, 5:39 PM

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there're serveral runtimeconfig.json in Celeste folder and they're all pointing at dotnet 8.0

calm hill Jan 25, 2026, 5:40 PM

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lyric pine send the `piton-runtime.yaml` file in your game files, and send the latest `log....

and these files for you

📎 piton-runtime.yaml 📎 log.txt

rapid pulsar Jan 25, 2026, 5:45 PM

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(01/25/2026 20:06:20) [Everest] [Info] [core] VersionCelesteString: 1.4.0.0-fna [Everest: 6129-azure-04aa4-stable]
(01/25/2026 20:06:20) [Everest] [Info] [core] SystemMemoryMB: 16003.219 MB
(01/25/2026 20:06:20) [Everest] [Info] [core] RuntimeVersion: 10.0.2

yeah its running on .net 10

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im not sure why it'd pick .net 10 here

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i've got these installed

lyric pine Jan 25, 2026, 5:51 PM

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calm hill and these files for you

can you try inputting dotnet E:\SteamLibrary\steamapps\common\Celeste\Celeste.dll in steam's custom launch arguments (without any %command% in it)

rapid pulsar Jan 25, 2026, 5:52 PM

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lyric pine can you try inputting `dotnet E:\SteamLibrary\steamapps\common\Celeste\Celeste.d...

why not just run it directly tbh

lyric pine Jan 25, 2026, 5:52 PM

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cause steam

rapid pulsar Jan 25, 2026, 5:52 PM

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right.

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go my steam_appid.txt

lyric pine Jan 25, 2026, 5:52 PM

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its honestly more work

calm hill Jan 25, 2026, 5:56 PM

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tried, not working

📎 log.txt

lyric pine Jan 25, 2026, 5:57 PM

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well then it has to be dotnet itself being goofy

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try updating everything maybe?

rapid pulsar Jan 25, 2026, 5:57 PM

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according to popax for some reason the .net resolver is trying to pick .net 10

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i wonder if there's a way to force just .net 8 to be picked

lyric pine Jan 25, 2026, 5:57 PM

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thats what runtimeconfig does

rapid pulsar Jan 25, 2026, 5:58 PM

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then why is it getting ignored

lyric pine Jan 25, 2026, 5:59 PM

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also, do you have a piton-runtime folder in your game files?

calm hill Jan 25, 2026, 5:59 PM

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no?

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rapid pulsar Jan 25, 2026, 5:59 PM

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i dont think piton would somehow download .net 10

lyric pine Jan 25, 2026, 6:00 PM

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just making sure :P

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but yeah thats what i was expecting

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can you remove dotnet 10 and see what happens?

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or does that force you to get rid of vs2026

rapid pulsar Jan 25, 2026, 6:14 PM

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lyric pine or does that force you to get rid of vs2026

you can't just remove the sdk thats installed with vs

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you're forced to remove the entire .net dev workflow

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stupid, i know

lyric pine Jan 25, 2026, 6:14 PM

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catplanet

calm hill Jan 25, 2026, 6:15 PM

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weheline i gotta try anyway

lyric pine Jan 25, 2026, 6:15 PM

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@rapid pulsar do you have vs2026?

rapid pulsar Jan 25, 2026, 6:15 PM

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nope

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i have 2022 but i could install

lyric pine Jan 25, 2026, 6:15 PM

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maybe that matters

rapid pulsar Jan 25, 2026, 6:15 PM

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id say its very likely lol

lyric pine Jan 25, 2026, 6:16 PM

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its still silly af tho

rapid pulsar Jan 25, 2026, 6:16 PM

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im removing 2022 first

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this will take a while

calm hill Jan 25, 2026, 6:29 PM

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what the heck

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it's not even producing a splash screen now

rapid pulsar Jan 25, 2026, 6:30 PM

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the hell

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it's being run with .net 9 now?

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@lyric pine uhhh can you call an exorcist

lyric pine Jan 25, 2026, 6:31 PM

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okay gonna get the ritual hold on

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so something really wants .net 10 huh

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is this with no vs2026?

calm hill Jan 25, 2026, 6:32 PM

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no i just removed dotnet 10 stuff( and alllll the dotnet things youknow

lyric pine Jan 25, 2026, 6:32 PM

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hmm okay

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soo dotnet --list-runtimes lists no .net 10 versions now right?

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but you still have the 9 and 8 and lower versions

calm hill Jan 25, 2026, 6:33 PM

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yeah

lyric pine Jan 25, 2026, 6:34 PM

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can you easily create a .net 8 app and try running it? or do you not know how to code in c#

calm hill Jan 25, 2026, 6:35 PM

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yes i'm just trying that

rapid pulsar Jan 25, 2026, 6:35 PM

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what if you just install the .net 8 runtime yourself lmao

lyric pine Jan 25, 2026, 6:35 PM

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they do have some .net 8 runtimes tho

rapid pulsar Jan 25, 2026, 6:35 PM

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yea ik

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but maybe that changes something

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just Console.WriteLine(Environment.Version); if you're making an app

lyric pine Jan 25, 2026, 6:37 PM

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yeah i just got snailed

calm hill Jan 25, 2026, 6:42 PM

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does that "Version=10" means that it's part of dotnet 10 standard library?

rapid pulsar Jan 25, 2026, 6:43 PM

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yes

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i dont know why it's trying to look for .net 10 stuff

calm hill Jan 25, 2026, 6:44 PM

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also i have removed vs2026

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there must be something thirst for .net 10 in my computer

rapid pulsar Jan 25, 2026, 6:47 PM

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does dotnet --list-runtimes and dotnet --list-sdks show anything .net 10

calm hill Jan 25, 2026, 6:47 PM

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obviously nothing about .net 10

rapid pulsar Jan 25, 2026, 6:48 PM

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weird as hell

rapid pulsar Jan 25, 2026, 6:49 PM

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calm hill

hold on did you compile this with .net 10

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try changing the target framework to net9.0 or net8.0

calm hill Jan 25, 2026, 6:50 PM

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no i just run a standalone dotnet.exe with the celeste.dll

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nothing code

rapid pulsar Jan 25, 2026, 6:50 PM

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oh right

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i thought it was your program

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i made a post somewhere else and they suggested to echo %DOTNET_ROLL_FORWARD% (or echo $env:DOTNET_ROLL_FORWARD if on powershell)

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what does that output

calm hill Jan 25, 2026, 6:52 PM

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LatestMajor

lyric pine Jan 25, 2026, 6:52 PM

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thats a bingo then

rapid pulsar Jan 25, 2026, 6:52 PM

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huh.

lyric pine Jan 25, 2026, 6:52 PM

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unset it

rapid pulsar Jan 25, 2026, 6:52 PM

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yeah for me it's empty

lyric pine Jan 25, 2026, 6:52 PM

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or set it to Disable

rapid pulsar Jan 25, 2026, 6:53 PM

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did you set the envvar yourself?

calm hill Jan 25, 2026, 6:54 PM

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no

rapid pulsar Jan 25, 2026, 6:54 PM

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i wonder if there's other envvars

calm hill Jan 25, 2026, 6:56 PM

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at least no other envvars' name contains "dotnet"

rapid pulsar Jan 25, 2026, 6:57 PM

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that's something

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so yea unset it and try running the game now

calm hill Jan 25, 2026, 6:58 PM

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vanilla ok, trying reinstall everest

rapid pulsar Jan 25, 2026, 6:58 PM

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vanilla uses .net framework

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so thats not exactly indicative of anything

calm hill Jan 25, 2026, 6:59 PM

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oh ok

rapid pulsar Jan 25, 2026, 7:00 PM

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@lyric pine installed vs2026, DOTNET_ROLL_FORWARD was not set for me

lyric pine Jan 25, 2026, 7:00 PM

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thankfully

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i mean they must have run some script that set it or something then

rapid pulsar Jan 25, 2026, 7:00 PM

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or they set it a long time ago and forgot

calm hill Jan 25, 2026, 7:04 PM

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it works

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fine...it's ,kind of my problem

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maybe

rapid pulsar Jan 25, 2026, 7:04 PM

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do you know how to unset envvars completely

calm hill Jan 25, 2026, 7:04 PM

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what do you mean

rapid pulsar Jan 25, 2026, 7:05 PM

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like, the envvar is probably set every boot

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do you know how to remove it

calm hill Jan 25, 2026, 7:05 PM

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i cant just search all text through my disk

rapid pulsar Jan 25, 2026, 7:05 PM

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no i know how to

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i was asking if you did

calm hill Jan 25, 2026, 7:06 PM

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no

rapid pulsar Jan 25, 2026, 7:06 PM

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anyways,

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windows+r, sysdm.cpl and enter

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go into environment variables

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check if DOTNET_ROLL_FORWARD is there anywhere

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if it is, delete it

calm hill Jan 25, 2026, 7:09 PM

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i thought you're about to tell me a way finding the script which "set the envvar every boot"

rapid pulsar Jan 25, 2026, 7:09 PM

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no lmao

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that'd be a nightmare

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i expected it to be somewhere inside that envvar list

calm hill Jan 25, 2026, 7:10 PM

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so the things you said is what i did

rapid pulsar Jan 25, 2026, 7:10 PM

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ah, great

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so we can now mark this as resolved

#Everest crashes during launching due to CoreCLR 10.0.2 not supported