When using the "Update an XML attribute using XPath" action it fails with the error:
Description: IOException while parsing the XML file
Release Automation 5.5.2
Using non Release Automation XPath tools (for ex: xmlstarlet sel -t -v "/your/xpath/@attribute" <filename>) showed that running the xpath query against the target .xml file returned a more helpful error - pointing to what the actual issue was so that you can go about fixing the xml file. Once the problem file was fixed xmlstarlet could successfully run an xpath query against the file and so could the Release Automation action.
You can likely find free xpath tools to test, but if you don't want to do this, then you may be able to open <NolioAgentInstallDir>/logs/nolio_all.log file and find more information about the error by searching for the error returned to you: IOException while parsing the XML file.
The message will be found and beneath that message should be the java exception raised when trying to run the xpath query against the xml file. The java exception will likely lead you in the right direction of what needs to be fixed. For example:
2016-04-08 16:41:51,597 [job-32775-jobServer-32775-6:Update an XML attribute using XPath - WORKING(P5962000.F5966000.E5967000):Update an XML attribute using XPath] ERROR (com.nolio.platform.shared.datamodel.Action:123) - IOException while parsing the XML file
java.io.FileNotFoundException: /tmp/myxmlfiles.dtd (No such file or directory)
at java.io.FileInputStream.open(Native Method)