txn fails with "previous operation failed" error

2020-10-02 05:30:50,130 | test  | ERROR   | Thread-150 | [rest_client:_http_request:747] POST http://172.23.105.229:8093/query?txid=e8ddcf04-4f66-4a6f-8425-bc536e1a1c73&scan_consistency=REQUEST_PLUS&statement=INSERT+INTO+default%3A%60UgD%60.%60-R%60.%60d9qWHq9GKA7rCiaOvTyo%60+%28KEY+k1%2C+value+t%29+SELECT+DISTINCT+t.name+AS+k1%2Ct+FROM+default%3A%60UgD%60.%60-R%60.%60d9qWHq9GKA7rCiaOvTyo%60+t+WHERE++job_title%3D%27Support%27+LIMIT+10+RETURNING+%2A body:  headers: {'Authorization': 'Basic QWRtaW5pc3RyYXRvcjpwYXNzd29yZA==\n'} error: 500 reason: unknown {

"requestID": "e354d8af-9d12-4f59-a5aa-fd6e8a31eaec",

"signature": {"*":"*"},

"results": [

],

"errors": [{"code":5000,"msg":"txFetch - cause: transaction operation failed | previous operation failed"}],

"status": "errors",

"metrics": {"elapsedTime": "1.213762152s","executionTime": "1.213616562s","resultCount": 0,"resultSize": 0,"serviceLoad": 3,"errorCount": 1}

} auth: Administrator:password