Hard to tell what's the root cause of it with the limited information you provided. But based on the error information, it might be Authentication issue when you post the payload against Maximo Rest API.
You can refer to my blogs regarding how to query and update data through Maximo NextGen rest API:
https://medium.com/eamstream/introduction-of-maximo-nextgen-rest-apis-part-1-query-maximo-data-6c082087e8f2
https://medium.com/eamstream/introduction-of-maximo-nextgen-rest-apis-part-2-update-maximo-data-e3db83751709
If you still have issue, more detail information would allow the experts here to help you out, such as what's OS, payload, authentication approach, etc.
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jacky qiu
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