Internal Server Exception to access Bedrock Knowledge Base

I wrote a code to access the Amazon Bedrock Knowledge Base and it worked successfully but now I am having the error below. How to fix it?

Exception occurred: An error occurred (InternalServerException) when calling the RetrieveAndGenerate operation (reached max retries: 4): Internal Server Exception

**Code: def askQuestion2(question): session = boto3.Session() bedrock_agent_runtime = session.client('bedrock-agent-runtime') request = { "input": {'text': question}, "retrieveAndGenerateConfiguration": { "type": "KNOWLEDGE_BASE", "knowledgeBaseConfiguration": { "knowledgeBaseId": "xxxxxxxxx", "modelArn": "arn:aws:bedrock:us-east-1::foundation-model/anthropic.claude-v2" } }, }