Magento 2.1.7 bug: Switching to the «Single-Store Mode» breaks the backend «Terms and Conditions» form: «htmlspecialchars() expects parameter 1 to be string, array given in vendor/magento/framework/Data/Form/Element/AbstractElement.php on line 286»

You are wrong: you have got this error not because you have «upgraded the stripe module via composer», but because you have enabled the «Single-Store Mode».

I have spent 2 hours and found out that Magento 2.1.7 contains a bug and incorrectly handles such situation.

The issue is not related to my extension.
I can solve such problems only on the terms of my generic Magento 2 paid support service.