Installed Forge 1.20.1, Ran the installer.jar but it just closes and creates a .log file.

 

JVM info: Oracle Corporation - 20.0.2 - 20.0.2+9-78
java.net.preferIPv4Stack=true
Current Time: 11/08/2023 16:29:01
Host: files.minecraftforge.net [51.79.83.165]
Host: maven.minecraftforge.net [51.79.83.165]
java.net.UnknownHostException: No such host is known (libraries.minecraft.net)
    at java.base/java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.base/java.net.Inet6AddressImpl.lookupAllHostAddr(Inet6AddressImpl.java:52)
    at java.base/java.net.InetAddress$PlatformResolver.lookupByName(InetAddress.java:1061)
    at java.base/java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1683)
    at java.base/java.net.InetAddress$NameServiceAddresses.get(InetAddress.java:1004)
    at java.base/java.net.InetAddress.getAllByName0(InetAddress.java:1673)
    at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1533)
    at net.minecraftforge.installer.DownloadUtils.getIps(DownloadUtils.java:290)
    at net.minecraftforge.installer.SimpleInstaller.main(SimpleInstaller.java:120)
Exception in thread "main" 
java.lang.NullPointerException: Cannot invoke "java.util.List.stream()" because the return value of "net.minecraftforge.installer.DownloadUtils.getIps(String)" is null
    at net.minecraftforge.installer.SimpleInstaller.main(SimpleInstaller.java:120)
 

It happens to me the same way and I still can't find the solution.

same problem, until a few days ago it was working perfectly now it just stopped working.

It happens to me too

same here with the same error

Same error 

It's the same for me

Same for me, 1.12.2 works fine but 1.20.1s forges just don't open and i wanted to play with my friend so i would need to install a server. If anybody has a server instalation pls send it to me. Btw a simple fix for this if you don't care for server hosting is installing it through curse forges launcher then forge works just fine but i need this server install

This is a known issue caused by Mojang abruptly removing one of their domain names. A fix is underway.

Announcement from the Forge discord: https://discord.com/channels/1129059589325852724/1129077934330744882/1212091927038533662

Invite link: https://discord.minecraftforge.net 

Download a fresh copy of the installer and it should be fixed.

https://discord.com/channels/1129059589325852724/1129077934330744882/1212138871907684382