MISTRAL API UPLOAD

The MISTRAL documentation indicates that text files (.txt) are accepted, as are PDF and DOCX and others. Indeed, with the CHAT function, a text file can be sent before a prompt is sended. Using the Mistral AI file API, I can easily upload a PDF file with the code shown below. However, if I try to upload a text file (the same that CHAT has accepted) I get an error message with The list of accepted formats : it does not include "text/plain," contrary to the list in documentation. Here is my code:

public async Task<string> UploadFileAsync(string filePath, string purposeTo = "ocr") { // 2 lines below are done in the constructor //_httpClient = new HttpClient(); //_httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", myApiKeyMistral); if (!File.Exists(filePath)) return ($"Erreur, fichier non trouvé: {filePath}"); FileInfo fileInfo = new FileInfo(filePath); if (fileInfo.Length == 0) return ($"Erreur, fichier vide : {filePath}"); string BaseUrlUpload = _baseUrlMistral + "files"; // in general "https://api.mistral.ai/v1/files" using var fileStream = File.OpenRead(filePath); using var fileContent = new StreamContent(fileStream); string mimeType = GetMimeType(filePath); // "application/pdf" if file is .PDF, text/plain if .txt, etc. fileContent.Headers.ContentType = MediaTypeHeaderValue.Parse(mimeType); using (var form = new MultipartFormDataContent()) { form.Add(fileContent, "file", System.IO.Path.GetFileName(filePath)); // "file" NOT "file_name" form.Add(new StringContent(purposeTo), "purpose"); try { var resp = await _httpClient.PostAsync(BaseUrlUpload, form); if (!resp.IsSuccessStatusCode) { // Gérez les erreurs ici string erreur = await resp.Content.ReadAsStringAsync(); return $"Erreur HTTP : {resp.StatusCode} - {resp.ReasonPhrase} - {erreur}"; } var json = await resp.Content.ReadAsStringAsync(); using var doc = JsonDocument.Parse(json); return doc.RootElement.GetProperty("id").GetString(); } catch (Exception ex) { return $"Erreur lors de l'upload du fichier : {ex.Message}"; } } }

Here the return error

Unprocessable Entity - {"detail": "Invalid file format.", "message": "Received file with mimetype text/plain, only application/pdf, image/.*, application/vnd.openxmlformats-officedocument.wordprocessingml.document, ... text/troff, text/x-dokuwiki are currently supported"}