400 bad Request error

Welcome to the Community.
 

Based on your description, it seems you're having trouble accepting client invites.
 

Here’s how you can troubleshoot this issue:

First, ensure your client sent the invitation to the correct email address. If the email address is correct but you still encounter an error, try clearing your browser's cache. Stored data can sometimes cause errors. If clearing the cache doesn’t fix the issue, switch to a different supported browser. This can help avoid browser-specific glitches.
 

You can also check this resource for more helpful tips: What to do if you can't accept client invites.
 

Let us know if you have additional questions or concerns.