Joao - We noticed the same error when upgrading to JDBC Adapter 6.0.3 and have opened an SR with wM Support. And actually, even if you install JDBC Adapter 6.0.3 from scratch, we ran into this issue. In the meantime, the following workaround resolved the problem:
create a directory called “…\packages\WmJDBCAdapter\code\jars\static”
put javasql.zip in this directory
If you’ll notice in your 6.0.2 instance of JDBC Adapter, this “static” directory exists. However, it doesn’t in 6.0.3 and therefore the “javaxsql” is not being sourced with version 6.0.3. This is probably because the server.sh/bat script doesn’t know where to find this package.