Transferring Apache-Superset Dashboard to Preset via JSON upload fails for particular dashboard

I have an old Superset dashboard which was backed up to JSON and I'm now trying to load into the hosted version of Preset. Other dashboards I've tested have loaded fine but the Preset GUI hangs when loading this one dashboard. There's no error displayed in the Preset GUI. The browser console returns a generic Error: 500. My assumptions are that either there is a cap on the size of the dashboard file that can be uploaded, or else my file is corrupt in some non-obvious way.

Is there a way of getting more detailed information on the error or else of validating the dashboard JSON template prior to upload?

Solution

From your description you might be impacted by two bugs that are currently affecting Preset Cloud:

Dashboard Import is not working if Charts excluded from the filters were removed from the Dashboard: This could be causing the 500 you are receiving.
Dashboard import operation dialog hangs when the operation fails: it seems that the import dialog is not throwing an error when it fails.

You can submit a support ticket on Preset Support page so that their support team can confirm if the root-cause is indeed that bug and help you modifying the file to import the Dashboard properly.