Gadget error 404 spec-not-found

Error 404 on GET https://jira.xxxxxx.xx/plugins/servlet/gadgets/error/spec-not-found which is a known Jira error for all addons, not just Tempo. Please try the following steps:

• Uninstall Tempo

• Remove the Gadget from the Dashboard

• Reinstall Tempo

• Insert the gadget again

Error in atlassian-jira.log:

[c.a.g.embedded.internal.GadgetUrlBuilder] GadgetUrlBuilder: could not parse spec at rest/gadgets/1.0/g/is.origo.jira.tempo-plugin:tempo-user-timesheet/gadgets/tempo-user-timesheet-gadget.xml