Is there currently an issue with the connection between QB and Paypal

Yes, there's an issue with the connection between QuickBooks and PayPal, vrhacommittee. With this, I recommend 

We have an ongoing investigation (INV-110535) where users are unable to connect their PayPal account with QuickBooks Online (QBO). Rest assured that this case is currently being worked on with utmost urgency.

While we're working on this matter, you can upload a CSV file of your transactions to keep your financial data updated. Once the issue is resolved, your latest transactions will automatically download to your QuickBooks account. Make sure to exclude any transactions you've already added to prevent duplicates.

In keeping with this, I'd recommend contacting our Customer Care team to add your account to the list of affected users. This ensures you're in the loop about the investigation's status and its fix. To do this, here's how:

1. Sign in to your QuickBooks Online company.
2. Go to the Help (?) menu.
3. Select the Search tab.
4. Search the QuickBooks Online knowledge base directly, or select the Contact Us button.
5. Enter a brief description of your concern and click Continue.
6. Choose a way to connect (Callback or Chat).

Additionally, I encourage you to reconcile your accounts regularly (monthly). Doing so will let you track your finances and manage them accordingly.

We'll be glad to have you back in the Community if you have other banking concerns or issues managing transactions in QuickBooks. Just click the Reply button, and we'll be ready to help you.

Thank you however my customers are unable to pay using PayPal 

they are contacting me saying when opening the invoice and select PayPal a message 'something went wrong our end' and are unable to go any further to pay the invoice 

Thanks for the prompt reply, @vrhacommittee.

Currently, the investigation about the QuickBooks and PayPal connection shared by my colleague above is still ongoing. That's why your customer is unable to pay using it.

In the meantime, your customer can utilize another payment method outside QuickBooks. Then, you can manually upload the payment transaction in QuickBooks using CSV file format.

Once done, match the imported payment transaction to the created invoice. Here's how:

1. Select Bank Transactions from the Transactions tab.
2. Click the payment transaction in the For Review section.
3. Pick Match and find the invoice for that payment transaction.
4. Then, click the box beside the invoice once you find it.
5. After that, select Match below.

Check out this article for more info: Match online bank transactions in QuickBooks Online.

Also, I agree with what my colleague suggested in contacting the QuickBooks Online (QBO) Care Team to add you as one of the affected users and be updated on the progress of the investigation.

You may want to learn how to personalise your sales form in QBO. Feel free to read this article: Customise invoices, quotes, and sales receipts in QuickBooks Online.

Click the Reply tab below if you have additional questions about managing your customer payments in QBO. We'll be willing to help. Keep safe, and enjoy the rest of the week.