"Internal" Error When Submitting Form With Firebase onCall Function on IOS Safari - ios

Question

I am trying to submit a form but I get an "internal" error after submit on IOS Safari. Happened on two separate devices. I'm using Firebase functions onCall function. Client code:
var contactForm =
window.firebase.functions().httpsCallable('contactForm');
let result = await contactForm({ accountUID, foldersFilter,
firstName, lastName, email, cellNumber, dobDay, dobMonth })
And server code:
exports.contactForm = functions.https.onCall(( data, context ) => {
return contactForm.contactForm( data, context )
});
This function is called via form. The form works great on chrome, safari desktop, but for some reason it gets an internal errror sometimes when testing on IOS device. At first I thought it only happened when I was using autofill, but I've tested more and I get the same error when not using autofill too.
The confusing thing is my function code is actually never being called (I don't see any firebase function logs). Here is my console in safari:
The network connection was lost.
Fetch API cannot load https://us-central1-projectId.cloudfunctions.net/contactForm due to access control checks
Failed to load resource: The network connection was lost.
internal
Why won't this form submit on ios safari?

Answer 1

I fixed the issue. Turns out it has something to do with Google Cloud Functions being IPv4, and Safari requiring IPv6. I suspect this will become a bigger issue moving forward. I'm having to move all onCall Firebase functions to https triggers. In order to make https triggers work, you have to use a custom domain in Firebase hosting and rewrite to your function endpoint.
{
"hosting": {
...
"rewrites": [
{
"source": "/api/contactForm",
"function": "contactForm"
}
}
and so now instead of calling https://us-central1-projectId.cloudfunctions.net/contactForm to trigger my api. I call https://customdomain.com/api/contactForm