I have downloaded the lastest Minecraft Forge sources (minecraftforge-src-1.6.1-8.9.0.775). I made simple ModLoader based mod (i know that this way of mod creation is deprecated - please don't write this, I need help for something else ). After I recompile it and get no errors, I start client from MCP. I get this error in minecraft window:

 

 

and this error in console: http://pastebin.com/LmZLpEAb.

 

I have tried making plain mod and also making mod in right way. Using @Mod(...). I got the same error. Is this my mistake or is this bug that needs to be fixed by forge developes?

 

NOTE: This message dissapears after 10 seconds and minecraft starts normaly. But I am developer of mod maker and users would find this annoying and I would need to put some kind of warrning message. Is there any option to get rid of this error message?

The log says it all.

[13:55:55] 2013-07-07 13:55:55 [sEVERE] [ForgeModLoader] Found a duplicate mod mod_TestEnvironmentMod at [C:\Users\(---)\workspace\(---)\mcp, C:\Users\(---)\workspace\(---)\mcp\bin\minecraft]

So remove it from one of these locations.

I haven't installed this mod. This is my mod and is located in MCP src. Then I recompile it and start client. Mod doesn't even exist in these folder. This location is provided by MCP - I think so

Actually this is a bug in MCP and will be addressed in our update to 1.6.2.

This only happened when using startclient correct?

Temporarily you can fix it by going to your conf folder and editng mcp.cfg

Find the line 'ClassPathClient = ' and make it 'ClassPathClient = conf'

Or just using eclipse to test for the time being.

As I said, small bug with MCP's adding things tot he classpath it shouldn't.

Will be fixed shortly.

Yes, that is true. And thanks for providing me fix.