Firebase hosting rewrite mapped to function fails with Internal Error

Question

I am using Firebase functions and exposing them through the following Firebase hosting rewrites:

{
"hosting": {
    "public": "build",
    "headers": [
        {
            "source": "/service-worker.js",
            "headers": [
                {
                    "key": "Cache-Control",
                    "value": "no-cache"
                }
            ]
        }
    ],
    "ignore": [
        "firebase.json",
        "**/.*",
        "**/node_modules/**"
    ],
    "rewrites": [
        // functions
         { "source": "/mappedUrlOne", "function": "functionOne" },
         { "source": "/mappedUrlTwo", "function": "functionTwo" },

        // landing page
        {
            "source": "**",
            "destination": "/index.html"
        }
    ]
}

When running repeated calls against the mapped URL (e.g. /mappedUrlOne) the functions intermittently fail about 50% of the time with a 500 Internal Error. The dropped requests don't even register in the Firebase logs and fail within 200-300ms.

If I call the function directly (e.g. https://us-central1-my-project-name.cloudfunctions.net/functionOne) everything goes smoothly.

The mappings have been deployed and working for a while, maybe over a year, so nothing's changed there.

Answer 1

Seems to have been an issue with GCP. Was fixed in a couple of hours without any changes.