Magento – Something went wrong with the subscription alert in Magento2

The only place I can find that exact string is in Magento_Ui/view/base/web/js/grid/provider.js in the function onError(). It looks like anywhere in the admin a grid is being used, this component is initialized. I would start by looking at your xhr requests in the chrome inspector network tab and finding any responses that don't return a 200 code. If you can confirm that this ajax request is related to the action that gave you that alert message, you can go from there.

You should check the var/logs folder to see if something went wrong and also your server logs.

For me the issue was related to this one https://github.com/magento/magento2/issues/5418.

Gone into db table cataloginventory_stock_item and delete duplicates and then the issue dissapeared.

If that doesn't solve it, you can try:

1) cd into pub/static and run find . -depth -name .htaccess -prune -o -delete

2) cd into root folder and run rm -rf var/cache/ var/generation/ var/page_cache/ var/view_preprocessed/

3) run php bin/magento setup:static-content:deploy

If this doesn't solve it you could take the radical option to reinstall:

1) delete the vendor folder rm -rf vendor/* and also the composer.lock file in root.

2) run composer install