Getting 502 Error

Hi there,
Seem you got wrong installation of our tool. Did you do full steps as indicated in the guide of our tool in the Readme.html (included file in your downloaded package)
Kindly provide me more information about your issues. I will check further and help you out.
Regards,
Mall.

Hi there,
Did you re-start your nginx server after your changing? Could you provide me full content of the nginx config file for your Magento2 site now? Does your server has a custom settings of the param named fastcgi_pass
Other case, could you contact to your system admin or hosting provider to get more help about some needed settings as guide for our tool?
Regards,
Mall.
 

Hi there,

…but seems like it wants me to re-import the categories + products

Yes, that is right. Because the v2.x of our tool has different engine process vs v3.x. 
Regards,
Mall.

Hi there,
It’s a hard situation.
As explained in previous reply, the engine of our old v2 version vs. new v3 is completely different.
And the Lite version is mainly for testing purpose only.
Because the sales data still associate with which products were purchased in each sale order, so it still require to migrate also categories and products. The issue is after re-migrating categories and products to M2, it’s impossible to merge such newly migrated data with the one you made changes.
Thanks for your understanding.
Regards,
Mall.

Hi bigpixel,
You already opened a your own thread so we’re going to answer you there instead.
Please help to follow up further in your own thread later instead of posting in multiple threads as it’s hard to keep track of.