Error while login microsoft teams

[Satender_Pal]

Error is - This username may be incorrect. Enter a different one or create a new one.

Our some students are facing this issue. Previously they are use there teams properly without any issue.

snapshot is attached for your kind information.

Please help... 

[#2 · Accepted solution]

@Satender_Pal  Hi i do see ou are using Firefox but have you tried using Microsoft Edge or Chrome, secondly is there a Microsoft team desktop client install so you can check on that, besides are all the users in this sub-domain having the same issue or just a few....can you also try creating an account on the main/root domain and check if that works.

even i would suggest checking the account exists on the Microsoft 365 admin center or not and having Microsoft Licesning assign.

[#3]

Make sure that the user has Internet access. Then, use the Network assessment tool to verify that the network and network elements between the user location and the Microsoft network are configured correctly. This is necessary to enable communication to the IP addresses and ports that are required for Teams calls

Regards,
Will