RemoveProtectionOperation ServiceApiException

ServiceApiException occurs when I use RemoveProtectionOperation

StackTrace

於 Adobe.DocumentServices.PDFTools.core.http.HttpClient.ExecuteRequest[T](HttpBaseRequest baseRequest)
於 Adobe.DocumentServices.PDFTools.core.http.HttpClient.<>c__DisplayClass11_0`1.<Execute>b__0()
於 Polly.Policy`1.<>c__DisplayClass11_0.<Execute>b__0(Context ctx, CancellationToken ct)
於 Polly.Retry.RetryEngine.Implementation[TResult](Func`3 action, Context context, CancellationToken cancellationToken, ExceptionPredicates shouldRetryExceptionPredicates, ResultPredicates`1 shouldRetryResultPredicates, Action`4 onRetry, Int32 permittedRetryCount, IEnumerable`1 sleepDurationsEnumerable, Func`4 sleepDurationProvider)
於 Polly.Retry.RetryPolicy`1.Implementation(Func`3 action, Context context, CancellationToken cancellationToken)
於 Polly.Policy`1.Execute(Func`3 action, Context context, CancellationToken cancellationToken)
於 Polly.Policy`1.Execute(Func`1 action)
於 Adobe.DocumentServices.PDFTools.core.http.HttpClient.Execute[T](HttpBaseRequest baseRequest)
於 Adobe.DocumentServices.PDFTools.core.api.CPFApi.CPFCreateOpsApi[T](InternalExecutionContext context, CPFContentAnalyzerRequests cpfContentAnalyzerRequests, List`1 sourceFileRefList, String operation)
於 Adobe.DocumentServices.PDFTools.core.service.RemoveProtectionService.RemoveProtection(InternalExecutionContext context, FileRefImpl sourceFileRef, String password, String operation)
於 Adobe.DocumentServices.PDFTools.pdfops.RemoveProtectionOperation.Execute(ExecutionContext context)
於 PDFHelper.Form1.button1_Click(Object sender, EventArgs e) 在 D:\FormTest\FormPDF\PDFHelper\Form1.cs:行 131 中