Hi, my user cann't accept my invitation and showing the error as sign in temporarily blocked

Thanks for posting your question in the Community forum, elodie.

When a user accepts an invitation by clicking the username link, it will prompt them to create an account or login using an existing account. Since they've encountered an error, let's isolate the issue to know it's caused by opening the invitation link using another browser. 

You can advise the user to use the keyboard shortcuts below:

• Chrome: Ctrl+Shift+N
• Internet Explorer: Ctrl+Shift+P
• Firefox: Ctrl+Shift+
• Safari: Command+Shift+N

Once done, have the user to accept the invite again. Check to see if it works. However, if the error persists, I recommend deleting and recreating the invite.

For additional reference, I'm including some resources on adding users:

• Add, delete, or change user access
• What different types of users can I add to my company?
• Add or remove an accountant

Please let me know how it goes. I'll be looking forward to hearing back from you. Have a great day!