Here you can learn about how to solve bflno is invalid warning message in E-invoice submission.
2. To solve this warning message, first open the Master module. Then select Organization menu. (fig.2)
3.Search the respective organization and click the edit option. (fig.3)
4. Now Click the Address tab and open the primary address page. (fig.4)
5. Now the enter the Territory/Area detail and click save button. (fig.5)
6. After added the Territory/Area detail, then open the E-invoice module. Then search the respective invoice which we want to submit. Then select the invoice. Click submit button and then click ok. (fig.6)
7. Now the E-invoice is be submitted successfully. (fig.7)
The above blog post explains about the how to solve bflno is invalid warning message in E-invoice submission.