BluePrint Spawn

Same problem with the blueprints in singleplayer? Log could be helpful.

What do you mean exactly with "red java errors"? Are they visible in the chat? In this case it's usually an error caused by a plugin (it should include some information about the plugin which caused this error). In case of doubt, a log file contains more information

If an error occurs in the game (e.g. caused by a bug), a dialog pops up (if it's a clientside issue) providing information about the hardware and the error, then the game closes. If a server side error (bug in the game) occurs (in multiplayer), the server shuts down (a file called "errorlog" will be created in the server directory), and all clients currently playing on the server receive a "losing connection" message in chat.

Only exception: errors which occur in plugins. When playing singleplayer, you will see the red output in chat. In multiplayer, only server admins receive this message (but the server log also contains information). These messages contain information about the plugin which caused this issue. It's a good idea to post the message here or forward it to the plugin creator (in most cases it's a bug in the plugin which can only be fixed by the plugin creator). If too many plugin-related errors occur, the server shuts down automatically btw (resulting in the "losing connection" message for all clients again).

In case of doubt, you could post a screenshot of the error here (or if you're the server admin, upload a server log [can be found in the "Logs" subfolder in the server directory] here or send it via PM to me)