I ran BuildTools.jar after installing the new version the way that the spigotmc website says. It runs properly until it reaches: "Final mapped jar: work/mapped.1ea8a6ae.jar does not exist, creating!" Then the program hits an error:

"Exception in thread "main" java.lang.OutOfMemoryError: Java heap space

             at net.md_5.ss.model.ClassInfo.getMethod(ClassInfo.java:39)

            at net.md_5.ss.remapper.EnhancedRemapper.findMethodDeclarer(enhancedRemapper.java:70)"

etc.

then:

"Exception in thread "main" java.lang.RuntimeException: Error running command, return status !=0: [java, jar, BuildData/bin/SpecialSource-2.jar, map, -i, work/minecraft_server.1.12.1.jar, -m BuildData/mapping$

            at org.spigotmc.builder.Builder.runProcess(Builder.java:555)

            at org.spigotmc.builder.Builder.main(Builder.java:313)

            at org.spigotmc.builder.Bootstrap.main(Bootstrap.java:23)

Please help!

Note: The same BuildTools.jar file worked on my other server with the same specs.