I can't upload webm, get jumbled error message

Tried on Firefox and Chrome, it says;

GRAPHQL ERROR (CODE: 413): {"RESPONSE":{"ERROR":"<HTML>\R\N<HEAD><TITLE>413 REQUEST

GRAPHQL ERROR (CODE: 413): {"RESPONSE":{"ERROR":"<HTML>\R\N<HEAD><TITLE>413 REQUEST

GRAPHQL ERROR (CODE: 413): {"RESPONSE":{"ERROR":"<HTML>\R\N<HEAD><TITLE>413 REQUEST

GRAPHQL ERROR (CODE: 413): {"RESPONSE":{"ERROR":"<HTML>\R\N<HEAD><TITLE>413 REQUEST

Is there an unstated size limit for files? Thanks