Api error status 409

Hi everyone,

I'm trying to upload a file using the javascript sdk, using node js.

But when i use the append method called filesUploadSessionAppendV2 is giving me the following error :

{ [Error: cannot POST /2/files/upload_session/append_v2 (409)]
status: 409,
text: '{"error_summary": "closed/", "error": {".tag": "closed"}}',
method: 'POST',
path: '/2/files/upload_session/append_v2' }

Anyone know what this error means?

Thank you in advance!