Error: The system cannot find the file specified - when multipart file upload and federated response

[oncicaradupopovici]

When doing a multipart file upload, and requesting data from multiple subgraphs I get the following errors:

open C:\Users\RPOPOV~1\AppData\Local\Temp\multipart-3224054384: The system cannot find the file specified.
Failed to fetch from Subgraph 'hcm-subgraph' at Path: 'executeHolidayRequestAction.document.replacementPerson'.
open C:\Users\RPOPOV~1\AppData\Local\Temp\multipart-3224054384: The system cannot find the file specified.
Failed to fetch from Subgraph 'hcm-subgraph' at Path: 'executeHolidayRequestAction.document.actions'.
open C:\Users\RPOPOV~1\AppData\Local\Temp\multipart-3224054384: The system cannot find the file specified.
Failed to fetch from Subgraph 'hcm-subgraph' at Path: 'executeHolidayRequestAction.document.workflowInstance'.

The mutation is executed successfully but other fetches from other subgraphs are never executed due to the errors above.

At this line temp files get deleted:

graphql-go-tools/v2/pkg/engine/datasource/httpclient/nethttpclient.go

Line 321 in a9be0ae

if err = os.Remove(file.Name()); err != nil {

Afterwards, at this line the files are loaded foreach subgraph involved in the federated response:

graphql-go-tools/v2/pkg/engine/resolve/loader.go

Line 1547 in a9be0ae

return source.LoadWithFiles(ctx, input, l.ctx.Files, res.out)

Maybe should clear the ctx.Files too when deleting the temp files, like: l.ctx.Files = nil

[Aenimus]

Hi @oncicaradupopovici

There aren't enough details here to help.

Furthermore, your link shows Cosmo router, which is part of the Cosmo repository. While Cosmo router is powered by graphql-go-tools, it looks like your question is much better placed there.

Please create a more informational, exhaustive, and reproducible issue report in the Cosmo repository. The issue template format should help you—please make sure it's all filled.

Thanks,

The WunderGraph Team

[oncicaradupopovici]

I belive the problem lies in this repo not in Cosmo Router.
The root cause of the issue is that the temp files used for multipart upload are deleted after the first subgraph request, but the same ctx.Files slice is reused for subsequent subgraph fetches. This leads to "file not found" errors when other subgraphs try to access the already-deleted files.

[devsergiy]

Hi @oncicaradupopovici

According to your findings, we think that omitting file removal here will fix the issue
We will make the change soon

Is it correct that you are uploading files to the different subgraphs?

[oncicaradupopovici]

Files are uploaded as part of the mutation to the first subgraph, but after executing the mutation, the router needs to fetch some fields from some other subgraphs in order to compose the result for the operation.

[devsergiy]

Could you share an operation?

[oncicaradupopovici]

{"operationName":"executeHolidayRequestAction","variables":{"request":{"id":"0","personId":59,"workflowInstanceId":"0","reasonLeftId":"23","dateFrom":"2025-06-03","dateTo":"2025-06-03","replacementPersonId":"1","attachment":{"name":"Report_CO_910.pdf","contentType":"application/pdf"}},"file":null,"workflowAction":"A_CO_SendToValidation","actionComments":null},"query":"mutation executeHolidayRequestAction($request: HolidayRequestActionInput!, $workflowAction: String!, $file: Upload, $actionComments: String) {
  executeHolidayRequestAction(
    request: $request
    workflowAction: $workflowAction
    file: $file
    actionComments: $actionComments
  ) {
    document {
      ...holidayRequest
      __typename
    }
    uiCommands {
      ...workflowUiCommand
      __typename
    }
    __typename
  }
}

fragment holidayRequest on HolidayRequest {
  id
  dateTo
  dateFrom
  availableDays
  daysNumber
  comments
  reasonLeft {
    ...reasonLeftDetailed
    __typename
  }
  replacementPerson {
    id
    displayName
    __typename
  }
  controls {
    ...workflowControl
    __typename
  }
  actions {
    ...workflowAction
    __typename
  }
  workflowInstance {
    id
    state {
      ...workflowState
      __typename
    }
    __typename
  }
  __typename
}

fragment reasonLeftDetailed on ReasonLeft {
  id
  name
  isHoliday
  __typename
}

fragment workflowControl on WorkflowControl {
  id
  name
  editable
  visible
  workflowInstanceId
  __typename
}

fragment workflowAction on WorkflowAction {
  id
  name
  displayName
  commentsAreMandatory
  withComments
  withCommentsMessage
  askAgain
  requiresValidation
  iconCode
  __typename
}

fragment workflowState on WorkflowState {
  id
  displayName
  color
  __typename
}

fragment workflowUiCommand on WorkflowUiCommand {
  commandName
  parameters
  __typename
}"}