Greetings mengwong,
It's odd that you are receiving an Error 70 when using the EOS R8 camera as a web cam. Using the UVC/UAC does not require the use of the EOS Webcam Utility. You may uninstall this app from your computer. Please also check to see if there are any other apps that may be trying to communicate with the camera through the USB cable. Please check to see if there is any security software or settings that may be interfering with how the EOS R8 communicates with the computer and with Zoom.
If using a USB hub to connect the camera to your computer, then let's try connecting the USB cable from the camera directly to a USB port on the computer or remove all of the other devices that may be connected to the USB hub. You may also test the camera with a different computer to see if the issue persists.
Usually, an Error 70 relates to an image related malfunction being detected by the camera. Please test to see if the same issue occurs when using the camera to record video to the memory card when the camera is not attached to the computer. Please also test a different memory card with the camera and please format the memory card within the camera prior to using it. Please note that formatting a card will erase all data from the card.
In case the issue persists, then we recommend on sending the unit to our facility for service.
Items purchased directly from Canon USA or from an Authorized Canon Dealer do include a one-year warranty if the item was purchased less than a year ago. You may view a list of Authorized Canon Dealers by clicking on the following link. I would recommend including a copy of your Proof of Purchase when sending in your item for the facility to review for any in-warranty service or repair.
https://www.usa.canon.com/internet/portal/us/home/contactus/where-to-buy/authorized-dealers
Canon U.S.A., Inc. has created a new online repair portal that allows you to set up service in a few simple steps. The repair portal gives you the ability to set up service for multiple pieces of equipment at once, and to receive a repair estimate in the majority of cases, depending on your model and issue. The portal also allows you to upload images or videos that will assist us in repairing your product. You can also select how you wish to be notified of the progress of your repair. The portal's service history section allows you to view all services that have been performed on any of your camera or video products since January 7, 2020.
Please follow the link below to access our online repair portal to arrange for service:
https://mycanon.usa.canon.com/signin
Instructions for Accessing and Using the Online Repair Portal.
You will need to access or create your My Canon Account.
If you already have a My Canon Account and your product is already registered, simply click on the “Get Repair Services” link on the left menu and follow the onscreen instructions to arrange for service for your product.
If you have a My Canon Account and your product is not registered, you must register your product first. Click on the “Get Repair Services” link on the left menu, then click on the “Register Product” link on the right. After your product is registered, click on the “Get Repair Service” link on the left menu and follow the onscreen instructions to arrange for service for your product.
If you do not have a My Canon Account, you will need to create one. After you create your account, click on the “Add Product” link to register your first product. After your product is registered, click on the “Get Repair Service” link on the left menu and follow the onscreen instructions to arrange for service for your product.
Once you have completed the repair request, you will have an opportunity to print a copy of the request for your records. This request form will also contain shipping instructions and an address label that you will attach to the outside of your shipping box when mailing your equipment for repair.
