my environment is magento 2.0.6
I installed a new payment module
if I remove my customized payment module, I can continue the checkout process.
if I enable my customized payment module, it failed and the exception error message is "Object DOMDocument should be created"
I tried my module on magento 2.0.7 and 2.0.6 and both failed.
So, I think the problem is the extension itself.
Can anyone help me and give me the direction where I can debug the root cause?