Jira Cloud rest API response 500

[Leon.Lee]

From about 12-12 18:13:00.975-CST to 12-12 19:52:46.082-CST 
our service requests the API, response 500, or timeout.

Can you tell me the reason？

error log:

/rest/api/3/jql/parse?validation=strict, ret:500, body:{"error":"APIRequestError","message":"Failed to make a request to the endpoint.  (endpoint = https://xxx/rest/api/3/jql/parse, method = POST, status_code = 0)","status_code":500,"successful":false}

The timeout period of 10000ms has been exceeded while executing GET /rest/api/3/issue/xxxxx?projectKeys=xxxx&expand=projects.issuetypes.fields