Understanding an Error Message

ActivityPub
1

Crosspost from Understanding an error message - lemm.ee

I’m trying to follow the instructions at How to implement a basic ActivityPub server - Mastodon Blog

I get the error message:
{"error":"Unable to fetch key JSON at https://<domain>/actor"}

The actor file is located at:
/var/www/<subdomain>/actor

that contains:

{
    "@context": [
        "https://www.w3.org/ns/activitystreams",
        "https://w3id.org/security/v1"
    ],

    "id": "https://<domain>/actor",
    "type": "Person",
    "preferredUsername": "alice",
    "inbox": "https://<domain>/inbox",

    "publicKey": {
        "id": "https://<domain>/actor#main-key",
        "owner": "https://<domain>/actor",
        "publicKeyPem": "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAnioC3W5cHbHLo+ln4QPm\n6EX1Ypvs5h+h47b5RwhF+2N84dSHXURUuA6a33+IlVqiO/3gGxIX+4MJuSDAxGZM\nWFDbuqDnHft2zWorKmIqyDzSSB/oMSqOVL8QV1KYWsCyhw9v2l5U6EIw2Z7u3Fc9\nW19dumK0ieL7CPME2dJGV5quBoa2AGg0D36XCp8hAWMXGUnlEcaqjyePJg9/quZn\no3W/+h5ujoUQG73SIUaJdsK16Q0E7o5N7JP7pqqE8p8pEXtpwXJJYE9y9ItTqvRS\na29xymyboCI6jSK+VTgjz1tj6W+EGQsPfka6t8Gq82NL00VxBEYb/eiEFuOSy4RL\ndwIDAQAB\n-----END PUBLIC KEY-----"
    }
}

I haven’t been able to find out what that error means. Is it unable to find the actor file? Maybe I should change /actor to /actor/ and put the file inside that? If so, what should the filename be?
Is it some problem with the public key inside the JSON? Is it mad about the newlines?

2

Hard to tell. Does https://<domain>/actor endpoint actually return a JSON object? If your server is public, you can verify your actor with this tool: https://verify.funfedi.dev

Also don’t forget to add the outbox property to your actor object, it is required by ActivityPub: ActivityPub

1 Like
3

Yes.
https://<domain>/actor
returns the JSON doc I posted above.

I added an outbox property. Same error message.

4

It must be served with a valid ActivityPub media type in the Content-Type header for the object, or else it will be rejected. Valid media types include application/ld+json; profile="https://www.w3.org/ns/activitystreams" or optionally application/activity+json. This is done as a precaution in recent versions of common ActivityPub server implementations, to prevent situations like misinterpreting the contents of an uploaded text file attachment being misinterpreted as a valid ActivityPub object (such as for impersonation of actors on the same domain).

5

Thanks for the tip.
I tried setting the Conent-Type and I get the same error though.

6

I have the same issue - i was working on a project couple of years ago which i got back to today and regular actor profile GET request that was previously returning json with remote actor data is now returning Unable to fetch key JSON <my local actor URL here> .