In Qlik sense i have face an issue that is when i try to open the dashboard it display the error message like "this app contains no data " . But after some time i used to open the same dashboard ,its opens fine without any issues.
1. Why its happens?
2. It happens due to that dashboard reload via QMC at that time when i open that dashboard ?
1. In most cases dashboards are imported into the QMC without data and then only populated with data upon reload. When there is no data in the dashboard (app), then you will get the this app contains nodata message. It could also be that the query used to populate your data model returned no values on the last reload and thus your app doesn't have any data in the data model.
If the same app sometimes has data and other times not, I would first investigate whether the query used to return the data maybe has a clause in which can mean that it can return no values. For example, inner joining on a table that can be empty or having an Exit Script in an if clause. If the app doesn't have data at first, but then always has data after that, then it probably means that it was imported without data.
2. No, the old data stays in the app until the next successful reload so that message wouldn't be caused by the reload of an app.
If the dashboard randomly doesn't have data and the QVDs always have data, then I think it might be something to log with Qlik support so that they can have a look. We have found that sometimes our QVDs aren't read/loaded as a result of anti-virus and we had one case where a developer had a conditional Exit Script which was added for testing, but not removed when the app was moved to production. Sorry for not being able to help you more.