Thank you. Problem automatically solved from quickbooks end after this post. I also remove my browser's data completely from my computer and sign in again with browser.

After that login into my quickbooks online accountant and load client's account.

Now I can access my client's company.
Thank you quickbooks team.

Hi ther Md Ekramul Hasan,

I'm happy to hear that you were able to log into your client's account so that you can assist with their books. If you have any other questions, feel free to reach out here.

Hello i am also facing this issue kindly resolve this issue please 

Hi Amna2,

It's essential that you're able to access your client accounts effortlessly.  I recommend opening your QuickBooks Online account using a private or incognito browser. You can use these keyboard shortcuts:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + P
• Safari: Command + Shift + N

Once you're signed in, proceed to access you client accounts. If you experience the same result, clear the cache on your browser.  If your browser has an excessive amount of frequently accessed page resources, it can cause some errors and/or unexpected behavior.

Should you require additional assistance, please don't hesitate to contact us outside of this forum.  Our Customer Care team will work with you in real-time and review the issue in more depth.  In addition, they'll be able to escalate it for further investigation with our Development team, if necessary.

Please don't hesitate to touch base with us again, if you have any other questions or concerns.  We would be happy to help!