Ugdhar

You should update to the latest launcher, mine shows 2.1.9616

Which launcher/version are you using?

I haven't tried making one myself yet, but someone posted this link not too long ago: https://gist.github.com/Commoble/ac7d7b57c9cbbfcae310c4ab110c3cc0 Hope that helps!

https://optifine.net/changelog?f=OptiFine_1.14.4_HD_U_F2.jar Changelog states it is not compatible with forge, try one of the newer ones, but check the changelog for that version to make sure it works with the forge version you want to use.

If the mod doesn't have a newer version past 1.7.10, you would either have to wait for the author to update it, or (with permission and source) update it yourself. Mods, for the most part, will only work with the version of forge they are built with.

You will need to update to a current (1.12.2+) version to receive support here. Those versions are really old, and no longer supported due to age.

I would suggest deleting and retyping the line it is pointing to, it looks like there's some kind of characters in there between the method name and the curly brace that don't belong, as opposed to a simple space.

You can find the logs and crash reports by looking in the minecraft game directory, which you specify in your installation, or the default would be C:\Users\<USERNAME>\AppData\Roaming\.minecraft Where did you download forge and your mods? Youtube has some userful information here and there, but it is also a cesspool of misinformation and bad crap. If you downloaded forge from ANYWHERE but here, or downloaded mods from anywhere besides the authors direct website, or from curseforge, I would delete them all and download them from the legit locations.

1.6.4 is no longer supported on these forums due to how old it is. Update to a more recent version (1.12.2+) to receive support.

Does it still crash if you remove Mo Creatures? It looks to me like that mod is causing the crash.

1.7.10 is no longer supported here due to its age. Update to a modern (1.12.2+) version to receive support here.

It looks like you posted the installer log, your game logs will be in the logs folder in the minecraft game folder

No, you can have all the versions of forge install at the same time if you want. What happens when you try to run it? How are you trying to run it?

That is still not the new launcher, did you redownload and reinstall from minecraft.net?

Please post complete logs as explained in the EAQ. This will give more information to help people help you.

1.7.10 is ancient, and no longer supported on these forums. For support here you will need to be using (I believe) 1.12.2+

You did not read the pixelmon website, you are using the wrong forge version.

I would guess one of the mods is poorly written, and is attempting to load client classes in a server environment. Unfortunately I can't tell which one it is, so unless someone else chimes in with the answer, you'll have to remove the mods one (or a few) until you figure out which one it is.

One of the mods is trying to access client classes on the server. Unfortunately I cannot tell which one, so all I can think is to remove mods a few at a time and see if they fix the crash, when it stops crashing, one of the mods you just removed is the culprit, start adding them back 1 by 1 and wait for the crash to identify the bad one.

Please post logs as explained in the EAQ to provide more information. Also, where did you download forge and your mods from? There is no forge that is compatible for 1.12-1.14, there are separate versions for each.

If you remove Optifine from the server, will it load? I believe Optifine is not meant for servers, only clients to increase performance.

You need to reassociate .jar files with Java, I believe there is a program out there called jarfix that does just that.

You need to upload your logs to pastebin or a github gist, and then post the link here. This will provide information for people to look and hopefully see what is crashing your minecraft. Otherwise we have no way of knowing what is going on!

Remove that mod and see if it still crashes. You should fully peruse your crashlogs, there is often (not ALWAYS, but often) a plain-english explanation.

You do not have the correct version of forge specified in the installation. The installation is using 2768, and Pixelmon 7.07 wants 2838, just like it says on the front of the pixelmon website.