I appreciate you for trying some troubleshooting steps before posting here, @saedsulub. 

I can sense a browser-related problem, and accessing sites using private mode prevents storing cache and cookies that might cause problems. 

Let your invited user accept the invitation using a private browser. Here's how: 

• Google Chrome: Hold Ctrl + Shift + N 
• Safari: Press Command + Shift + N
• Microsoft Edge or Mozilla Firefox: Hit Ctrl + Shift + P 

If the problem persists, I'd recommend contacting our Customer Care team to help you check what's causing this to happen. They can request to investigate the issue whenever necessary. 

For future reference, check out this article to know more about transferring the role to manage your books: Change your master admin user.

I'd be glad to help you again if you need further assistance in managing your QuickBooks company. 

Unfortunately, I have tried to use incognito browser but still the problem persists. The QBO customer service is not responsive at all. The toll number I called told me that they only serve US customers. QBO should let us know if they no longer support international version so we can look for alternatives. 

I have attached the error message with this post. 

@saedsulub 

Open a trial account to isolate the issue. Did you encounter the same error message?

https://quickbooks.grsm.io/Asia-Pacific

Yes I have tried that. The problem still persists. Unfortunately, no response at all from QBO customer service.

Hi there, saedsulub. 

Thanks for letting me know that you've tried the basic troubleshooting steps provided by my colleague above. 

Since the issue still persists, I'd suggest contacting our Customer Care Team. This way, they can check your account using their tools and perform a screen-sharing session. Also, they'll investigate why the issue still happens on your end and might create an open investigation with this.

Here's how to reach them:

1. Click the Help menu in the upper-right-hand corner.
2. Type in "Talk to a human", then press Enter.
3. Look for I still need a human and click on it.
4. Click Get help from a human or Contact Support Team.
5. Select between Send a message, Schedule an appointment, or Get a callback.

You can check out this article for our most updated contact information and scheduled hours: Support hours and types.

If you want to transfer the role to a new user, you may see this article for the detailed steps: Change your master admin user.

Let me know if you need further assistance in managing your QuickBooks company. You can reach out to the community or me at any time. Take care.