403 Forbidden - Import Spaces using CSV file

[FERNANDO FRANZOTT BORGO]

Im extracting a CSV file from a old Jira Cloud Platform and now i want to import the same space in the new Jira Cloud Platform. 

I pass for all pages, but at the moment to import the CSV file, the system returns the following error for many rows:

Row 34 - [403 Forbidden] during [GET] to [http://atlassian-proxy.mesh:20027/cloudid/e489cfa4-8b5e-48ec-88e5-8f79543664ca/jira/rest/api/3/attachment/meta] [JiraCloudClient#getAttachmentSettings(StringString)]: [{"message":"ASAP token from issuer 'micros/jira-x2c-executor' failed authorization"

How can i fix it?