If an app depends on a custom connector we do not currently support exporting the connector as a part of the package.
If you have an app that relies on a custom connector, your only current option is to manually re-create or update the connector in your target environment and select that connector when you import the package.
Check if above is the cause of your issue.
Community Support Team _ Mona Li If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
Thank you for the answer, i read that my sql connector may not packaged. But the problem is I still can't export my app, even without this resource. After i click "export package" i get blank page with gray export button.