How to fix TargetFileAlreadyExists error

I consistently get the following error when I have translated several different files: azure.core.exceptions.HttpResponseError: (TargetFileAlreadyExists): Target document file already exists.

127.0.0.1 - - [10/Jul/2025 10:23:40] "POST /translate_document HTTP/1.1" 500 -

The first files will translate ok but after 2 or 3 tests it fails until I clear the source/target storage containers.

Files are unique and have UUIDs so believe something else is causing issue. Help please!

here is the full translate route:

@app.route('/translate_document', methods=['POST'])
def translate_document():
    if 'file' not in request.files:
        return jsonify({'error': 'No file uploaded'}), 400

    file = request.files['file']
    if file.filename == '':
        return jsonify({'error': 'Empty filename'}), 400

    try:
        # Generate unique filename
        original_filename = file.filename
        unique_filename = f"{uuid4()}_{original_filename}"

        # Get container client
        container_client = blob_service_client.get_container_client(target_container_name)

        # List all blobs in the translations/ folder
        print("Current blobs in 'translations/':")
        for blob in container_client.list_blobs(name_starts_with="translations/"):
            print(" -", blob.name)

        # Check if any blob ends with the original filename
        for blob in container_client.list_blobs(name_starts_with="translations/"):
            if blob.name.endswith(original_filename):
                print(f"Found existing translation: {blob.name}")
                sas_token = generate_blob_sas(
                    account_name=account_name,
                    container_name=target_container_name,
                    blob_name=blob.name,
                    account_key=account_key,
                    permission=BlobSasPermissions(read=True),
                    expiry=datetime.utcnow() + timedelta(hours=1)
                )
                translated_file_url = f"https://{account_name}.blob.core.windows.net/{target_container_name}/{blob.name}?{sas_token}"
                return jsonify({'download_url': translated_file_url})

        #  Delete any blob that ends with the original filename (to avoid Azure conflict)
        for blob in container_client.list_blobs(name_starts_with="translations/"):
            if blob.name.endswith(original_filename):
                print(f"Deleting conflicting blob: {blob.name}")
                container_client.delete_blob(blob.name)

        # Wrap file with new filename to ensure uniqueness inside the blob
        file_content = file.read()
        file.seek(0)
        wrapped_file = FileStorage(
            stream=BytesIO(file_content),
            filename=unique_filename,
            content_type=file.content_type
        )

        # Upload to source container
        blob_client = blob_service_client.get_blob_client(container="sourcefolder", blob=unique_filename)
        blob_client.upload_blob(wrapped_file, overwrite=True)

        # Construct target container URL
        target_url = f"https://{account_name}.blob.core.windows.net/{target_container_name}/translations?{target_container_sas_token}"

        # Determine language pair
        source_lang = "en"
        target_lang = request.form['target_language']
        lang_pair = f"{source_lang}-{target_lang}"
        glossary_url = glossary_urls.get(lang_pair)

        # Build translation target
        targets = [
            TranslationTarget(
                target_url=target_url,
                language=target_lang,
                glossaries=[
                    TranslationGlossary(
                        glossary_url=glossary_url,
                        file_format="Csv"
                    )
                ] if glossary_url else None
            )
        ]

        print("Glossary is being applied:", bool(glossary_url))

        # Start document translation
        input = DocumentTranslationInput(
            source_url=source_container_url,
            targets=targets
        )
        poller = document_translator.begin_translation(inputs=[input])

        # Print debug info BEFORE waiting for result
        print("Original uploaded filename:", original_filename)
        print("Unique filename (blob name):", unique_filename)
        print("Glossary URL used:", glossary_url)
        print("Target language:", target_lang)
        print("Source container URL:", source_container_url)
        print("Target container URL:", target_url)

        # Wait for result
        result = poller.result()

        for doc in result:
            print(f"Document status: {doc.status}, translated URL: {doc.translated_document_url}, glossary URL: {getattr(doc, 'glossary_document_url', 'N/A')}")
            print("Translated blob name:", doc.translated_document_url)

        # Generate SAS token for the newly translated file
        translated_blob_name = f"translations/{unique_filename}"
        sas_token = generate_blob_sas(
            account_name=account_name,
            container_name=target_container_name,
            blob_name=translated_blob_name,
            account_key=account_key,
            permission=BlobSasPermissions(read=True),
            expiry=datetime.utcnow() + timedelta(hours=1)
        )

        translated_file_url = f"https://{account_name}.blob.core.windows.net/{target_container_name}/{translated_blob_name}?{sas_token}"
        return jsonify({'download_url': translated_file_url})

    except Exception as e:
        print("Exception occurred during document translation:")
        traceback.print_exc()
        return jsonify({'error': str(e)}), 500



    
if __name__ == '__main__': app.run(debug=True)