I can't send invoices

Hi there, @info1869. 

I'm here to help you fix this error. I'd like to know what error you have seen when you send an invoice. I'd really appreciate any screenshot or error codes you can provide so that I can look for a specific resolution.

There are times that the data saved in the browser has caused this odd behavior. This is because the accumulated data saved in the cache will become outdated over time. For now, I recommend running some basic troubleshooting steps to check if it's cache-related. At times, too much cached accumulated in a browser can cause unexpected behavior with the product. To start, open your account using a private window. Simply press the following shortcut keys to access this mode:
 

• Ctrl + Shift + N (Google Chrome).
• Ctrl + Shift + P (Firefox).
• Control + Option + P (Safari).

Once done, try sending invoices again. If you're able to successfully send them, clear the cache in your regular browser. Alternatively, you can use other supported browsers. 
 

I've added this article that can be handy for your future task about handling recurring invoices in QuickBooks Online: Create the same invoice for multiple customers.

Additionally, you're able to email and print multiple invoices and other sales forms in QBO. This way, you're able to save time and effectively monitor your sales transactions. You can learn more about this through this article: Email or print multiple invoices and sales forms.

You're always welcome if you need further assistance with sending invoices. We're always here to lend a helping hand.