Why I receive 500 Internal Server Error on Postman when I run a flask app

Question

Dears,

I am new to Python and flask. When I run the following code on Spyder I get the following message:

runfile('C:/Users/...../Desktop/Folders/..../BlockChain/Create Blockchain/Module 1 - Create a Blockchain/blockchain.py', wdir='C:/Users/...../Desktop/Folders/..../BlockChain/Create Blockchain/Module 1 - Create a Blockchain')
 * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)

but when I want to run http://127.0.0.1:5000/get_chain on POSTMAN, I get the following message:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<title>500 Internal Server Error</title>
<h1>Internal Server Error</h1>
<p>The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.</p>

I TOTALLY CONFUSED WHY? Here is my code:

import datetime
import hashlib
import json
from flask import Flask, jsonify, request

Part 1 - Building a Blockchain

class Blockchain:

    def __init__(self):
        self.chain = []
        self.create_block(proof = 1, previous_hash = '0')

    def create_block(self, proof, previous_hash):
        block = {'index': len(self.chain) + 1,
                 'timestamp': str(datetime.datetime.now()),
                 'proof': proof,
                 'previous_hash': previous_hash}
        self.chain.append(block)
        return block

    def get_previous_block(self):
        return self.chain[-1]

    def proof_of_work(self, previous_proof):
        new_proof = 1
        check_proof = False
        while check_proof is False:
            hash_operation = hashlib.sha256(str(new_proof**2 - previous_proof**2).encode()).hexdigest()
            if hash_operation[:4] == '0000':
                check_proof = True
            else:
                new_proof += 1
        return new_proof

    def hash(self, block):
        encoded_block = json.dumps(block, sort_keys = True).encode()
        return hashlib.sha256(encoded_block).hexdigest()

    def is_chain_valid(self, chain):
        previous_block = chain[0]
        block_index = 1
        while block_index < len(chain):
            block = chain[block_index]
            if block['previous_hash'] != self.hash(previous_block):
                return False
            previous_proof = previous_block['proof']
            proof = block['proof']
            hash_operation = hashlib.sha256(str(proof**2 - previous_proof**2).encode()).hexdigest()
            if hash_operation[:4] != '0000':
                return False
            previous_block = block
            block_index += 1
        return True

# Creating a Web App

    app = Flask(__name__)

# Creating a Blockchain

    blockchain = Blockchain()

# Mining a new block

    @app.route('/mine_block', methods = ['GET'])

    def mine_block():
        previous_block = blockchain.get_previous_block()
        previous_proof = previous_block['proof']
        proof = blockchain.proof_of_work(previous_proof)
        previous_hash = blockchain.hash(previous_block)
        block = blockchain.create_block(proof, previous_hash)
        response = {'message': 'Congratulations, you just mined a block!',
                    'index': block['index'],
                    'timestamp': block['timestamp'],
                    'proof': block['proof'],
                    'previous_hash': block['previous_hash']}
        return jsonify(response), 200

# Getting the full Blockchain

    @app.route('/get_chain', methods = ['GET'])
    def get_chain():
        response = {'chain': blockchain.chain,
                    'length': len(blockchain.chain)}
        return jsonify(response), 200

# Checking if the Blockchain is valid

    @app.route('/is_valid', methods = ['GET'])
    def is_valid():
        is_valid = blockchain.is_chain_valid(blockchain.chain)
        if is_valid:
            response = {'message': 'All good. The Blockchain is valid.'}
        else:
            response = {'message': 'Houston, we have a problem. The Blockchain is not valid.'}
        return jsonify(response), 200


# Running the app

    app.run(host='0.0.0.0', port=5000)

Answer 1

Flask is not compatible with that. Need to upgrade our Flask. how to do:

step 1: Open Anaconda prompt
step 2: write command conda install flask=1.0.0 now your flask will get update..& issue will get solve if, still don't work, then downgrade Werkzeug how to do:
- step 1: conda install Werkzeug=0.16.1 in Anaconda prompt.

And Restart the Anaconda.

Answer 2

'is_xhr' method has been deprecated & removed, So you need to upgrade your Flask version

Open Anaconda Prompt and type

pip install --upgrade Flask

Then restart your IDE

Why I receive 500 Internal Server Error on Postman when I run a flask app

Question

2 answers

solution1
0 2020-08-14 06:16:02

solution2
0 2021-03-05 05:48:43

Why I receive 500 Internal Server Error on Postman when I run a flask app

Question

2 answers

solution1 0 2020-08-14 06:16:02

solution2 0 2021-03-05 05:48:43

solution1
0 2020-08-14 06:16:02

solution2
0 2021-03-05 05:48:43