Go to Jira Administration → System → Advanced - Attachments

In that menu, increase the limit value to upload attachments, according to the size of attachment that is being uploaded

Example:


If the size of the Execution Results file is higher than the limit value configured, when importing the Execution Results file the following error is shown:


Important note: Increasing this value may lead you with timeout issues.


This is not related to the Xray REST API.

Link for the related documentation

Test Execution#ImportExecutionTestResults