Quickbooks app (uk) won't let me edit an invoice for some reason? Error message pops up to contact support...

I recognize the urgency of sorting this issue with your invoices, rhoganproton.

I'm here to route you in the right direction for support so you can fix and edit them seamlessly in QuickBooks Online (QBO).

As for the pop-up error message, I recommend reaching out to our Customer Care Support Team so our representatives can look into your account in a safe environment and find the root cause of this issue about editing your invoices in the QBO mobile app. This way, they can guide you with the possible resolution.

Here's how:

1. From the Search tab, click Contact Us.
2. Enter your question and select Continue.
3. Review and select from the following: Have us call you or Chat with us.

Moreover, this article can help you account for your customer payments in the future: Receive invoice payment.

I’m always ready to assist you if you have any other questions or concerns about invoices or your sales transactions in QBO. Keep safe always.