I'm also having the same problem. the first time I launched Forge without any mods it launched with no problems. but after I added some mods to my mods folder, it kept on crashing
This was what the output log was showing...
17:55:13.877
Preparing to launch minecraft client for 1.17.1-forge-37.0.75
17:55:16.967
Checking installations.
17:55:16.970
Minecraft client 1.17.1-forge-37.0.75 is ready to start.
17:55:16.970
Starting!
17:55:19.318
Version does not support log configuration, will assume one plaintext entry per line
17:55:24.655
2021-10-02 17:55:24,625 main WARN Advanced terminal features are not available in this environment
17:55:25.123
[17:55:25] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--username, Dezpiez, --version, 1.17.1-forge-37.0.75, --gameDir, C:\Users\user\AppData\Roaming\.minecraft, --assetsDir, C:\Users\user\AppData\Roaming\.minecraft\assets, --assetIndex, 1.17, --uuid, --erased this myself--, --accessToken, ????????, --userType, msa, --versionType, release, --launchTarget, forgeclient, --fml.forgeVersion, 37.0.75, --fml.mcVersion, 1.17.1, --fml.forgeGroup, net.minecraftforge, --fml.mcpVersion, 20210706.113038]
17:55:25.130
[17:55:25] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 9.0.7+91+master.8569cdf starting: java version 16.0.1 by Microsoft
17:55:25.424
Exception in thread "main" java.lang.module.ResolutionException: Module OptiFine._1._17._1.HD.U.G9 contains package net.minecraftforge.eventbus.api, module eventbus exports package net.minecraftforge.eventbus.api to OptiFine._1._17._1.HD.U.G9
17:55:25.425
at java.base/java.lang.module.Resolver.resolveFail(Resolver.java:908)
17:55:25.425
at java.base/java.lang.module.Resolver.failTwoSuppliers(Resolver.java:814)
17:55:25.425
at java.base/java.lang.module.Resolver.checkExportSuppliers(Resolver.java:743)
17:55:25.425
at java.base/java.lang.module.Resolver.finish(Resolver.java:379)
17:55:25.425
at java.base/java.lang.module.Configuration.<init>(Configuration.java:140)
17:55:25.425
at java.base/java.lang.module.Configuration.resolveAndBind(Configuration.java:494)
17:55:25.425
at MC-BOOTSTRAP/
[email protected]/cpw.mods.modlauncher.ModuleLayerHandler.buildLayer(ModuleLayerHandler.java:70)
17:55:25.425
at MC-BOOTSTRAP/
[email protected]/cpw.mods.modlauncher.ModuleLayerHandler.buildLayer(ModuleLayerHandler.java:82)
17:55:25.425
at MC-BOOTSTRAP/
[email protected]/cpw.mods.modlauncher.TransformationServicesHandler.discoverServices(TransformationServicesHandler.java:129)
17:55:25.425
at MC-BOOTSTRAP/
[email protected]/cpw.mods.modlauncher.Launcher.run(Launcher.java:86)
17:55:25.425
at MC-BOOTSTRAP/
[email protected]/cpw.mods.modlauncher.Launcher.main(Launcher.java:77)
17:55:25.425
at MC-BOOTSTRAP/
[email protected]/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:26)
17:55:25.425
at MC-BOOTSTRAP/
[email protected]/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:23)
17:55:25.425
at
[email protected]/cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:90)
17:55:25.531
Process crashed with exit code 1