RAG_PLAYGROUND - Error loading Knowledge Base Files

Hi,

Using Basic Examples, langchain or llamaindex, upload_button fail to upload .txt or .pdf files in "kb.py" file line 39
with gr.Row():
upload_button = gr.UploadButton("Add File", file_types=["pdf","txt"], file_count="multiple")

gradio.exceptions.Error: "Invalid file type. Please upload a file that is one of these formats: ['pdf', 'txt']"
Thanks for your help!

log below:

milvus-standalone | [2025/06/15 15:08:03.033 +00:00] [WARN] [dist/dist_handler.go:112] ["node last heart beat time lag too behind"] [now=2025/06/15 15:08:03.033 +00:00] [lastHeartBeatTime=2025/06/15 15:07:42.235 +00:00] [nodeID=14]
rag-playground | [1] Jun 15 15:07:46 [ INFO] - uvicorn.access - 172.20.0.1:45696 - "POST /content/kb/gradio_api/upload HTTP/1.1" 200
rag-playground | [1] Jun 15 15:07:46 [ INFO] - uvicorn.access - 172.20.0.1:45696 - "POST /content/kb/gradio_api/queue/join?__theme=light HTTP/1.1" 200
rag-playground | Traceback (most recent call last):
rag-playground | File "/usr/local/lib/python3.10/dist-packages/gradio/queueing.py", line 625, in process_events
rag-playground | response = await route_utils.call_process_api(
rag-playground | File "/usr/local/lib/python3.10/dist-packages/gradio/route_utils.py", line 322, in call_process_api
rag-playground | output = await app.get_blocks().process_api(
rag-playground | File "/usr/local/lib/python3.10/dist-packages/gradio/blocks.py", line 2216, in process_api
rag-playground | inputs = await self.preprocess_data(
rag-playground | File "/usr/local/lib/python3.10/dist-packages/gradio/blocks.py", line 1882, in preprocess_data
rag-playground | processed_input.append(block.preprocess(inputs_cached))
rag-playground | File "/usr/local/lib/python3.10/dist-packages/gradio/components/upload_button.py", line 190, in preprocess
rag-playground | return [self._process_single_file(f) for f in payload] # type: ignore
rag-playground | File "/usr/local/lib/python3.10/dist-packages/gradio/components/upload_button.py", line 190, in
rag-playground | return [self._process_single_file(f) for f in payload] # type: ignore
rag-playground | File "/usr/local/lib/python3.10/dist-packages/gradio/components/upload_button.py", line 157, in _process_single_file
rag-playground | raise Error(
rag-playground | gradio.exceptions.Error: "Invalid file type. Please upload a file that is one of these formats: ['pdf', 'txt']"
rag-playground | [1] Jun 15 15:07:46 [ INFO] - uvicorn.access - 172.20.0.1:45696 - "GET /content/kb/gradio_api/queue/data?session_hash=6jcjgqfkk19 HTTP/1.1" 200

Start with kb.py around line 39 and reproduce the upload using the Basic Examples flow with both .txt and .pdf files. Check the Gradio UploadButton validation shown in the traceback; done means both supported file types upload successfully without the Invalid file type error.