We develop portlets using exo platform on top of jboss eap 6.2. When we include an upload button in our zul files, it sometimes fails with error: 'The server is temporarily out of service.'. The steps are;
1. we click the upload button
2. a window for file browser opens
3. we click the select button after selecting one or many files
4. it gives the error I wrote above.
After we clear the caches of the browser it works. and after some time it fails again.