I'm trying to install Forge for 1.12.2. The installer runs properly and says it installed forged succesfully, but when I go into the launcher there is no Forge profile and forge isn't in the version list when cresting a custom profile. In the versions folder in .minecraft the forge 1.12.2 folder is there, but it only has the .json file, it seems that the installer is not actually getting the .jar file. I tried with both the recommended and latest installers. I also tried downloading the universal .jar directly and pasting it into the versions folder but that didn't work either.

 

Installer log:
JVM info: Oracle Corporation - 1.8.0_371 - 25.371-b11
java.net.preferIPv4Stack=true
Found java version 1.8.0_371
Extracting json
Considering minecraft client jar
Downloading libraries
Found 0 additional library directories
Considering library net.minecraftforge:forge:1.12.2-14.23.5.2859
  File exists: Checksum validated.
Considering library org.ow2.asm:asm-debug-all:5.2
  File exists: Checksum validated.
Considering library net.minecraft:launchwrapper:1.12
  File exists: Checksum validated.
Considering library org.jline:jline:3.5.1
  File exists: Checksum validated.
Considering library com.typesafe.akka:akka-actor_2.11:2.3.3
  File exists: Checksum validated.
Considering library com.typesafe:config:1.2.1
  File exists: Checksum validated.
Considering library org.scala-lang:scala-actors-migration_2.11:1.1.0
  File exists: Checksum validated.
Considering library org.scala-lang:scala-compiler:2.11.1
  File exists: Checksum validated.
Considering library org.scala-lang.plugins:scala-continuations-library_2.11:1.0.2_mc
  File exists: Checksum validated.
Considering library org.scala-lang.plugins:scala-continuations-plugin_2.11.1:1.0.2_mc
  File exists: Checksum validated.
Considering library org.scala-lang:scala-library:2.11.1
  File exists: Checksum validated.
Considering library org.scala-lang:scala-parser-combinators_2.11:1.0.1
  File exists: Checksum validated.
Considering library org.scala-lang:scala-reflect:2.11.1
  File exists: Checksum validated.
Considering library org.scala-lang:scala-swing_2.11:1.0.1
  File exists: Checksum validated.
Considering library org.scala-lang:scala-xml_2.11:1.0.2
  File exists: Checksum validated.
Considering library lzma:lzma:0.0.1
  File exists: Checksum validated.
Considering library java3d:vecmath:1.5.2
  File exists: Checksum validated.
Considering library net.sf.trove4j:trove4j:3.0.3
  File exists: Checksum validated.
Considering library org.apache.maven:maven-artifact:3.5.3
  File exists: Checksum validated.
Considering library net.sf.jopt-simple:jopt-simple:5.0.3
  File exists: Checksum validated.
Considering library org.apache.logging.log4j:log4j-api:2.15.0
  File exists: Checksum validated.
Considering library org.apache.logging.log4j:log4j-core:2.15.0
  File exists: Checksum validated.
Considering library org.apache.logging.log4j:log4j-slf4j18-impl:2.15.0
  File exists: Checksum validated.
Building Processors
Injecting profile
Finished!

I am unable to replicate this.

Regardless, the version you are using is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Currently, supported versions are 1.19.4 (Latest) and 1.18.2 (LTS).