Can't Open or Execute a Workbook After the Upgrade Due to NullPointerException

Problem 

After the upgrade, one or more workbooks can't be opened or executed due to java.lang.NullPointerException

From conductor.log

ERROR [2018-04-18 09:15:34.686] [JobScheduler thread-1] (JobScheduler.java:670) - Failed to start job.
java.lang.NullPointerException
ERROR [2018-04-18 09:14:37.724] [qtp683287027-128472] (DasExceptionFilter.java:43) - Unhandled exception handling /workbook/1234
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:808)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1669)
at datameer.dap.conductor.webapp.filter.HeaderInjectFilter.doFilter(HeaderInjectFilter.java:24)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)

Cause

This might happen due to issues that occurred during the workbook migration process that runs at the first post-upgrade service launch. If this process was interrupted or failed, you might face the above mentioned behaviour.

Solution

Re-save the workbook by opening Configure menu and pressing the Save button (no changes required). In case this workaround doesn't work or isn't acceptable, please get in touch with Datameer support for further investigation.