Hi there, damian5.
For some reason, there are times that software like QuickBooks will not work properly. It's when our data is holding too much cache. If that's the case, we will be experiencing unusual behavior and getting some unexpected messages. We can troubleshoot this one by following the steps below. It helps us to verify if it's really a browser issue that causing this unusual behavior.
If your client hasn't tried to sign in their account using a private browser. You can let them follow the shortcut keys below, depending on what browser they're using.
- Google Chrome: Ctrl + Shift + N
- Microsoft Edge: Ctrl + Shift + P
- Firefox: Ctrl + Shift + P
- Safari: Command + Shift + N
If they're able to link the invoice without getting the message, we can go back to our main browser and clear the cache. This is to start your data fresh and help QuickBooks to work well. Also, you can use other supported browsers like Mozilla, Google Chrome, Microsoft Edge, and Safari. For Safari, make sure to use the latest one.
If the same thing happens, you can let your client delete the invoice. Then, resend it to them.
Leave your reply below if you still need a hand with this matter. I'll always around to help. Take care!