This error seems to be the same one described on this topic: https://answers.atlassian.com/questions/24653287/how-to-link-a-service-desk-to-a-confluence-space
Can you confirm you have enabled 2 legged oauth in JIRA? See this article: https://confluence.atlassian.com/display/SERVICEDESK/Providing+self-help+resources+for+your+customers+with+a+knowledge+base#Providingself-helpresourcesforyourcustomerswithaknowledgebase-Troubleshootingissueswith2-LeggedOAuth
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