I'd like to help you get this fixed, WAFabs.

May I know what is the specific error message you're getting after opening the invoice? In the meantime, we can do some troubleshooting steps to investigate if the issue has something to do with your browser's cache.

Sometimes, these file cache gets corrupted and can cause unusual behaviors in the program. This can be resolved by clearing the cache. However, let's test it out by opening your QuickBooks Online account in an incognito or private browser. This mode doesn't store any browsing history.

Here are the keyboard shortcuts:

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

After signing in, try to open the invoice. If it works, go back to your regular browser and clear its cache. Once done, close and re-open your browser to refresh the settings.

You can try using a different supported browser as an alternate solution.

Please let me know how it goes after trying out the steps. I'll be right here to help you until a solution is found. Stay safe!