we have a astra site with toolset and experience the same issues after updating both astra an toolset, no importing scenario here but still the same problem:
Warning: call_user_func_array() expects parameter 1 to be a valid callback, cannot access private method Astra_Addon_Background_Updater::needs_db_update() in /home/..../public_html/domains/***/wp-content/plugins/wp-views/vendor/toolset/toolset-theme-settings/compatibility-modules/controllers/toolset-theme-integration-settings-front-end-controller.php on line 363
I would like to inform you that the fix for the issue is shipped with Views version 3.1.0.
Could you please update ALL Toolset plugins to it's latest officially released version. You can download the latest plugin release from your accounts page:
=> https://toolset.com/account/downloads/