jira-azuredevops-migrator: Problem with the attachments

Hi, all seems fine except with the attachements. I have the following message with a ticket (during the JIRA import step) :

[E][18:34:42] Cannot find info for attachment '12604'. Skipping.
[System.InvalidOperationException] System.InvalidOperationException: Response Status Code: 404. Response Content: {"errorMessages":["La pièce jointe avec l'ID '12604' n'existe pas"],"errors":{}}
   at Atlassian.Jira.Remote.JiraRestClient.GetValidJsonFromResponse(IRestRequest request, IRestResponse response)
   at Atlassian.Jira.Remote.JiraRestClient.<ExecuteRequestAsync>d__10.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at JiraExport.JiraProvider.<GetAttachmentInfo>d__18.MoveNext():
   at Atlassian.Jira.Remote.JiraRestClient.GetValidJsonFromResponse(IRestRequest request, IRestResponse response)
   at Atlassian.Jira.Remote.JiraRestClient.<ExecuteRequestAsync>d__10.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at JiraExport.JiraProvider.<GetAttachmentInfo>d__18.MoveNext()
[E][18:34:42] Unexpected migration error.
[System.AggregateException] System.AggregateException: One or more errors occurred. ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at JiraExport.JiraProvider.<DownloadAttachmentAsync>d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at JiraExport.JiraProvider.<DownloadAttachments>d__27.MoveNext()
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at JiraExport.JiraMapper.MapAttachments(JiraRevision rev)
   at JiraExport.JiraMapper.MapRevision(JiraRevision r)
   at JiraExport.JiraMapper.<>c__DisplayClass8_0.<Map>b__2(JiraRevision r)
   at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at JiraExport.JiraMapper.Map(JiraItem issue)
   at JiraExport.JiraCommandLine.ExecuteMigration(CommandOption user, CommandOption password, CommandOption url, CommandOption configFile, Boolean forceFresh)
---> (Inner Exception #0) System.NullReferenceException: Object reference not set to an instance of an object.
   at JiraExport.JiraProvider.<DownloadAttachmentAsync>d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at JiraExport.JiraProvider.<DownloadAttachments>d__27.MoveNext()<---
:
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at JiraExport.JiraMapper.MapAttachments(JiraRevision rev)
   at JiraExport.JiraMapper.MapRevision(JiraRevision r)
   at JiraExport.JiraMapper.<>c__DisplayClass8_0.<Map>b__2(JiraRevision r)
   at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at JiraExport.JiraMapper.Map(JiraItem issue)
   at JiraExport.JiraCommandLine.ExecuteMigration(CommandOption user, CommandOption password, CommandOption url, CommandOption configFile, Boolean forceFresh)

All the process is stopped, so the import is not correctly finished. Does someone could help me please ? thx