Taverna 1.7.x error messages

Taverna 1.7.x error messages can sometimes be difficult to understand. Some common errors are explained here:

• Unable to open Xscufl file – occurs when Taverna is unable to parse the workflow file that you tried to open. This may be because it is not a valid workflow definition, or because Taverna is unable to access some of the services within the workflow. You should check that you are connected to the Internet.
• Could not establish connection … The server uses more recent protocol than… when using the Rshell service. You need to use the correct version of the R server.
• Unable to create scavenger! Unable to load the WSDL definition, underlying reason was … when loading a new WSDL scavenger. This can occur if the WSDL is generated by Axis2 and is a known bug in some Axis2 versions.
• Error occured during invocation Content is not allowed in prolog – indicates that you are attempting to pass non-XML input into a service (normally a WSDL service) that expects an XML file. You should add XML splitters so that the data can be wrapped appropriately.
• … SVG … font-weight:regular – some versions of GraphViz can generate invalid SVG (for the diagram). This is a known GraphViz bug. You may need to change to a different version of GraphViz.
• …java.lang.LinkageError: duplicate class definition – this is a known Taverna bug.
• java.io.FileNotFoundException for a nested workflow – this commonly occurs when you have downloaded or copied a workflow that contains a nested workflow. The path to the nested workflow has been stored in the parent workflow definition, but can no longer be reached e.g. it was on a local machine. Workarounds for this problem have been suggested.
• java.lang.UnsupportedClassVersionError: net/sf/taverna/tools/BootstrapClassLoader – this occurs if you try to run Taverna 1.7.x in a version of Java earlier than 1.5. Check that you are using a correct version of Java, e.g. with java -version.
• Unable to determine file for mygrid.properties – This suggests that the $taverna.home property is not set correctly.