Inquiry Regarding 403 Error on REST API Attachment Upload (Jira v9.12.26)

[mg l]

Hello, Jira Support Team,

We are currently using a self-hosted Jira server, version v9.12.26#9120026.

I am writing to inquire about an issue I'm encountering with the REST API for handling attachments.

Here is the situation:

1. My goal is to download an attachment from a specific Jira ticket and then upload it to a different ticket using the REST API.

2. I have confirmed with our internal Jira administrator, and they have stated that there are no specific restrictions configured on their end that should prevent this action.

3. While I can successfully download the attachment via the REST API, the upload process fails with the following HTTP 403 error: JIRAError: JiraError HTTP 403 ... text : You are not allowed to upload this file type. Please get your Jira admin to update the Attachment Checker configration

Could you please clarify whether this is a known bug in Jira version 9.12.26, or if this error definitively points to a server-side configuration issue that our administrator may need to adjust?

Thank you for your assistance.

Best regards,