Flutter using cloudflare stream tus upload got 400 error

First of all, it was grateful from your helping.

Now I solved the step 4 ERROR CODE 400 it’s because the mini chunk that stream required…

But I have another questions while I adopted direct creator upload

Scenario I:(direct creator upload)

SEND POST request

====> the upload url contains in ‘Location’ header is https://upload.videodelivery.net/tus/9ad9e32ec59da27c16a3f56523f78b7d?tusv2=true

i send a HEAD request carries header below, it received 502 BAD Gateway

Scenario II: (NOT direct creator upload)
SEND POST request to

====> the upload url contains in ‘Location’ header is https://api.cloudflare.com/client/v4/accounts/ACCOUNT_ID/media/MEDIA_ID?tusv2=true

Scenario II worked well, then video uploading will be completed with several PATCH request.

how to solve this issue.

thanks a lot