My friend has this error when logging in to his premium account:

[xMelonekMaX]

latest.log

When he logs in, he is shown information about the login page and the code to use.

Quilt Loader 1.20.1
IAS 9.0.0-beta.4

[VidTu]

unable to reproduce. it seems you have corrupted JAR (Caused by: java.lang.RuntimeException: Failed to load class file for 'ru.vidtu.ias.utils.Holder'!) and/or the mod JAR has been deleted while the game was running (Caused by: java.nio.channels.ClosedByInterruptException)

[VidTu]

unable to reproduce

[xMelonekMaX]

I guess it's the same mistake here. The file's hashcode matches the one downloaded from the website
latest (1).log

[VidTu]

it looks like some sort of race-condition in the quilt loader itself (since not able to reproduce on fabric/forge), use -Dloader.workaround.jar_copy_all_mods=true JVM flag as a temporary workaround for now

[VidTu]

related to QuiltMC/quilt-loader#431.
fixed in 0a6a8b3.
will be released in the future. (test builds can be downloaded here)

[VidTu]

Fixed in 9.0.0-beta.5.

[xMelonekMaX]

On 9.0.0-beta.5:
latest.log

[VidTu]

no internet connection

[xMelonekMaX]

https://youtu.be/Dwi65rV05PQ?si=Kk8vDzRzKeYcC4XR

This tutorial solved the problem. Is there a way to work around this problem as only Feather and IAS had this problem. Everything worked on Lunar Client all the time.

[VidTu]

i would certainly neither install nor use the client that modifies my "hosts" file without BIG RED warning about it. it's like a malware. for what purpose should a minecraft launcher (or to be fair, any program, except those designed for software piracy, content blocking, or for parental/employee controls) should block my internet traffic?