Merchant processing stopped working. error 500

Thanks for the input, @SilexOrange. I'll share updates about the error encountered when processing payments and point you in the right direction to resolve the error prompt encountered after the QuickBooks Desktop (QBDT) system update.

Please note that there are similar cases or reports about the HTTP STATUS 500 - Internal Server Error when processing payments inside QBDT. I recommend contacting our Customer Care Team so they can include you in the affected users' list and receive updates once a fix for this specific prompt is available. I'll outline the steps below to get you going:

1. Access your QuickBooks Desktop company.
2. Go to Help, then select QuickBooks Desktop Help/Contact Us.
3. Enter the question, keyword, or topic you need help with.

For more details, refer to this article: Get help with QuickBooks products and services.

On top of that, I recommend checking this article and working with an IT expert for a possible solution to this since it's a problem with the script function where it blocks payment processing inside the program: Script error when using payments account applications or websites.

If other questions about QuickBooks arise, I can always provide ways to assist you in sorting them out. You can post here in the Community space or comment below so I can answer your queries. Keep safe.

I am having the same issue after the update.  I get the exact same errors when I try to process credit card payments.  

Same here as well, and disabling the antivirus things only allowed us to process 1 payment and then we continued getting the error again afterwards.

Hello there, @Systassoc and @jeffp07.

I regret hearing about your experience, please understand that this is not the level of service we aim for you to encounter, especially after the update. It can be a challenging situation, but please know that I'm here to help and support you every step of the way.

We have received reports from other users who are experiencing the same error regarding HTTP STATUS 500 - Internal Server Error when processing payments in QuickBooks Desktop (QBDT). Our engineering team is currently investigating the issue and working on a resolution.

Therefore, I recommend reaching out to our QuickBooks Support team to subscribe to the notification list for affected users. You will receive an email once there are developments regarding the investigation, including the permanent solution. Here's how:

1. Access your QuickBooks Online (QBO) company, go to Help (?).

2. Choose either of these tabs:

• Assistant tab and type Talk to a human.
• Search tab and click on Contact Us to connect with a support expert.

3. Select the preferred method of contact (phone or chat).

Furthermore, here is an article you can use in case you encounter script errors executing a command that involves our application(s) on your computer attempting to access a web-based (internet) feature: Script error when using payments account applications or websites.

Additionally, you may need to configure your firewall or security software to ensure uninterrupted access when using QuickBooks Payments: Configure firewall or security software when using QuickBooks Payments.

Rest assured that our engineers are actively working to resolve this issue. We greatly appreciate your patience as we address this matter. Should you have any other concerns about error 500 when processing payments in QBDT, leave a comment below and I'll be glad to provide the information you need. Take care and have a good one!

I just tried to process credit cards again and it is 'magically' working.  No changes to my firewall or antivirus.  Possibly QB fixed the issue.  However, I didn't think they could fix things that fast...so hopefully, it really is fixed and not temporary