please help

Because.. your world doesn't save the mods on your server or client? That's not at all related to the world itself

If your getting the error message “Failed to synchronic registry data from server” then check the following:

1)The client side forge/fabric version should match the server side forge/fabric version

2)The mods installed on your Minecraft client (your PC) including the versions need to match the mods installed on your server (Exceptions like sodium and other client side mods)

3)If the forge/fabric version and the mods installed match then try deleting the config folder which is located in the minecraft installation path (enter %appdata%/.minecraft in the file explorer )

Share your client log:

1. open your minecraft installation path (enter %appdata%/.minecraft in the file explorer )
2. open the logs folder

3. open the "latest" or "latest.log" file with a text editor

4. copy and paste the content of the file to https://mclo.gs/

5. send the link here

Share your log:

1.) Go to your log on Aternos: https://aternos.org/log/

2.) Click on the big blue "Share" button on the top right

3.) Copy the link with (Ctrl + C or click on the "Copy" button)

4.) Send the link here.

According to the client log the mods on your pc with the versions don't match the mods on your server.

So you installed the mods through tlauncher right? I would suggest you to download the mods with the correct versions from their curseforge page and putting in mods folder.

You need to download the forge installer and run that

Quote from Powerful845tiger

According to the client log the mods on your pc with the versions don't match the mods on your server.