I'm running the latest version of Forge (build 738) on an MCPC+ (build 649) server for 1.5.2, and the client has the same MC and Forge version.

Both client and server OS are Win 7 Ultimate x64 and my Java version reports it's JRE 7 Update 45, although I have both x64 and x86 versions of both jre6 and jre7 on the client and server computers.

 

When any user tries to connect to the server, they are disconnected with a message that says "Internal server error", and the server console shows the following error: https://gist.github.com/anonymous/ec40cb3b30237593bd25

 

The entire log file is at https://gist.github.com/anonymous/8dbc985e9cc9fcbe3e40/.

 

I have already tried adding the 1.5.2 forge lib files to the lib folder on the server, which only had the files starting in "asm" and "deobfuscation" prior. The client already had all the files. The missing files from the server lib folder appear to be only needed in the client, as they are not marked as in-use when the server is running.

I have also tried copying the jacob-1.17-M2-x86 and x64 dll files into each of my java installation bin folders (x64 jre6, x64 jre7, x86 jre6, and x86 jre7).

I redownloaded the latest Forge build for the client and renamed it to modpack.jar. The only thing in the old modpack.jar was Forge as well.

The version of MCPC I'm using works on an FTB Unleashed server where the client is running Forge build 737.

Also, this issue was tested with Forge builds 734 and 738 on the client, both with the same result.

 

If you need any more information, just ask me. I'm glad to provide anything you need to help fix this issue!

I'm running the latest version of Forge (build 738) on an MCPC+ (build 649) server

 

MCPC+ is not an official build of forge. You should probably take it up with the MCPC+ guys.

 

Also, a 1.5.2 server is very old now - and as such would not get any support here anyway.