Getting errors while building a PDF QA with OPEN AI & Langchain

Question

I am trying to use Langchain & AI. So, I have installed all the libraries and tried to write the below code with Langchain documentation. But I seem to face some errors which I am not able to resolve.

Here is my code:

import os
from langchain.document_loaders import PyPDFLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain.vectorstores import Chroma
from langchain.embeddings import OpenAIEmbeddings
from langchain.chat_models import ChatOpenAI
from langchain.chains import RetrievalQA

os.environ['OPENAI_API_KEY'] = 'OPenAi key'

persist_directory = "./storage"
loader = PyPDFLoader("sodapdf-converted.pdf")
documents = loader.load()

documents = loader.load()

text_splitter = RecursiveCharacterTextSplitter(chunk_size=512, chunk_overlap=10)
texts = text_splitter.split_documents(documents)

embeddings = OpenAIEmbeddings()
vectordb = Chroma.from_documents(documents=texts, 
                                 embedding=embeddings,
                                 persist_directory=persist_directory)
vectordb.persist()

retriever = vectordb.as_retriever(search_kwargs={"k": 3})
llm = ChatOpenAI(model_name='gpt-4')

qa = RetrievalQA.from_chain_type(llm=llm, chain_type="stuff", retriever=retriever)

while True:
        user_input = input("Enter a query: ")
        if user_input == "exit":
            break

        query = f"###Prompt {user_input}"
        try:
            llm_response = qa(query)
            print(llm_response["result"])
        except Exception as err:
            print('Exception occurred. Please try again', str(err))

And I am getting the following errors:

Traceback (most recent call last):
  File "c:\Users\ansha\OneDrive\Documents\Python\HOA Search\Langchain\test.py", line 21, in <module>
    vectordb = Chroma.from_documents(documents=texts,
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\langchain\vectorstores\chroma.py", line 564, in from_documents
    return cls.from_texts(
           ^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\langchain\vectorstores\chroma.py", line 528, in from_texts
    chroma_collection.add_texts(texts=texts, metadatas=metadatas, ids=ids)
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\langchain\vectorstores\chroma.py", line 166, in add_texts
    embeddings = self._embedding_function.embed_documents(list(texts))
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\langchain\embeddings\openai.py", line 478, in embed_documents
    return self._get_len_safe_embeddings(texts, engine=self.deployment)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\langchain\embeddings\openai.py", line 328, in _get_len_safe_embeddings
    response = embed_with_retry(
               ^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\langchain\embeddings\openai.py", line 107, in embed_with_retry
    return _embed_with_retry(**kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\tenacity\__init__.py", line 289, in wrapped_f
    return self(f, *args, **kw)
           ^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\tenacity\__init__.py", line 379, in __call__
    do = self.iter(retry_state=retry_state)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\tenacity\__init__.py", line 314, in iter
    return fut.result()
           ^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\concurrent\futures\_base.py", line 449, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\concurrent\futures\_base.py", line 401, in __get_result
    raise self._exception
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\tenacity\__init__.py", line 382, in __call__
    result = fn(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\langchain\embeddings\openai.py", line 104, in _embed_with_retry
    response = embeddings.client.create(**kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\openai\api_resources\embedding.py", line 33, in create
    response = super().create(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\openai\api_resources\abstract\engine_api_resource.py", line 153, in create
    response, _, api_key = requestor.request(
                           ^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\openai\api_requestor.py", line 298, in request
    resp, got_stream = self._interpret_response(result, stream)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\openai\api_requestor.py", line 700, in _interpret_response
    self._interpret_response_line(
  File "C:\Users\ansha\AppData\Local\Programs\Python\Python311\Lib\site-packages\openai\api_requestor.py", line 763, in _interpret_response_line
    raise self.handle_error_response(
openai.error.AuthenticationError: Incorrect API key provided: cjbZWnFC************************************xYfa. You can find your API key at https://platform.openai.com/account/api-keys.

Please ignore the Incorrect API Key error.