Blocking request from unknown origin – Jupyter

n any of these platforms the server is listening on the given port


Starting version 1.6 or later can find a list of open tabs with the following info…

Open tab # Show the tabs

Here’s an example from the GitHub repo:

All open tabs # All on the server

Here’s a snapshot from the GitHub repo:

Open a new tab, open the following tabs. See if you can find an unmodified extension that fits this tab. # The following command should be used to open those tabs. # The following command should work here.

You may also be interested in:



After all this configuration, the server is listening on port, and the server listening on port 4667, so we can change some of the output using the following instructions:

After that, a server-list file should be created to store the list

You can do this with the following commands when opening these tabs:

The notebook server failed to start – Jupyter notebook

You are getting the message The notebook server failed to start: Invalid connection. Try again later.

What caused the problem? Please refer to our technical help link.

How to troubleshoot the notebook server failure

If you experienced a problem not listed above with this notebook server please use our troubleshooting tips for the notebook server.

What is the exact cause of the problem with the notebook server?

The notebook server is not up to date; the notebook server itself is not updated

The notebook server server may be on an incorrect network address. Please check on the network address at your chosen time

If your notebook server is offline in an area of the universe, try changing the server address and doing a restart of your notebook server, and make a backup. The notebook server will not see your changes but you will not be able to restore it.

How should I fix the laptop problem when the server crashes?

If a problem with the notebook server is not listed above, please refer to our technical help link for assistance in solving the notebook server problems.

What is the cause of the problem with the laptop?

This notebook server is not up to date. It may be out of date or being downgraded.

ClubHouse Android – how to install clubhouse on Android?

Clubhouse is an audio-based social media application. This article describes how to install it on clubhouse android app. The company describes itself as “a new kind of voice-based social product that enables people around the world to speak, tell stories, develop ideas, deepen friendships and meet new people.” Basically, you can get in and out of different discussions on different topics through live podcasts. You can just listen or choose to post your thoughts. Imagine a cocktail party or a clubhouse.


Clubhouse is an audio platform. In the digital “room” people can chat in real time. So far, iPhone users can only use this feature after receiving an invitation from a registered user. Registered users can create personal profiles, open new “rooms” together, and announce their conversations in the calendar so that others can listen to them. The moderator chairs the discussion by turning the audience into speakers or cutting off participants again. If they wish to name the host as the speaker, they can raise their hand.

Installer Clubhouse sur iOS

The Clubhouse iOS app lets you work with your team even on the go.

Download Clubhouse to find, create and edit stories anytime, anywhere, and access your workspace, space, dashboard, and event feed from your iPhone, iPad, or iPod touch.

The Clubhouse iOS app can be used with any device running iOS 9.0 or higher.

1. Find the club in the App Store

2. Press the get button

3. Tap Open to start the app.

Install Clubhouse on Android

The Clubhouse Android app lets you work with your team even on the go.

1. Find the club in the Google Play Store

2. Press the install button Google Play Store

3. After installation, click “Open” to start the application.

Source :

Clubhouse audio application android availability

Clubhouse mentioned Android apps in their last blog post in January 2021.

The post is essentially an important announcement from the company that it has committed to opening the app to “the world” in 2021.

But Google users should see this change soon: Obviously, that’s not the release date.

In fact, it’s not even the start date for development. What we do know is that so far Clubhouse is specific to iOS, and the company has announced that it will start developing its Android apps. This can mean that it will come out several months or even years later. We just don’t know that.

Internal links clubhouse apk

External links

ImportError: cannot import name ‘jitclass’ from ‘numba’ (/opt/conda/lib/python3.7/site-packages/numba/

You get this error with python when you try from numba import jit, jitclass

How to fix : cannot import name ‘jitclass’ from ‘numba’ (/opt/conda/lib/python3.7/site-packages/numba/

You only need to import differently jitclass :

From :

from numba import jitclass

You need to use now :

from numba.experimental import jitclass

Internal links :

The algorithm for mining bitcoin in Python

This article describes a python implementation of bitcoin mining that relies on an algorithm based on a double hash SHA-256.

Introduction – Principle of the bitcoin mining agorithm

Miners on the bitcoin network should look for the nonce which is a 32-bit number. The miner will successively test several NONCEs (1,2,3 …. 10 ^ 32-1), for each of the nonce he creates the following header and hasher twice with a SHA-256 bit hash function.

versionVersion 4
Hash previous block256-bit hash of the previous block32
Merkle rootThis is a hash on the data in the block. It is provided to the miner and it contains a summary of the transactions that are contained in the block.32
timeA digital timestamp that represents the number of seconds since 1970-01-01T00: 00 UTC4
bitsThe current target in compacted format4
nonce32-bit number (starts at 0)4

Once the hash obtained, the miner must then check that the hash obtained is lower than the target difficulty factor of the block. If the hash obtained is greater then the nonce is not the correct one, another must be tested.

Example on block 671712

If you are using a blockhain bitoin explorer (for example blocstream info), if we take for example block 671712:

In this case here is an algorithm in python which allows to mine this block:

In this simulation I display the header and the calculated hash as well as the hash rate.

The nonce to find for block 671712 was 4107802144

in hexadecimal : 0xf4d81620

This algorithm starts with a nonce = 4107802144 – 400 we will act as if we were very close to finding the block (400 double hashes are missing to find the block):

import hashlib
from hashlib import sha256
import time
import struct
import binascii
import datetime
from binascii import unhexlify, hexlify
from dateutil import parser
from datetime import datetime
from datetime import timedelta 

nontrouve = True
dtprec =
inonc = 4107802134 - 400 #Starting 400 before the good nonce
resultat = []

    inonc +=1
        print(str(round(timedelta(seconds=1)/( - dtprec))) + ' H/s')
    dtprec =
    header_hex = (binascii.hexlify(struct.Struct('<L').pack(int('0x2fffe000',16))).decode()  + 
     binascii.hexlify(binascii.unhexlify('c504fc3a406f11c7c5b598da7f50916f4e298041e6f9b91535a80db113af109a')[::-1]).decode() +
     binascii.hexlify(struct.Struct('<L').pack(int(hex(int(parser.parse('2021-02-22 15:14:22 GMT +1').timestamp())-3600),16))).decode() +
     binascii.hexlify(struct.Struct('<L').pack(int("0x170cf4e3",16))).decode() + 
    header_bin = unhexlify(header_hex)
    dt1 ="%H:%M:%S.%f")
    hash = hashlib.sha256(hashlib.sha256(header_bin).digest()).digest()
    MAX_TARGET = int("00000000FFFF0000000000000000000000000000000000000000000000000000", 16)           
    Difficulty = 21724134900047.27                     
    target = int(MAX_TARGET / Difficulty)
    target32 = '{:0>64x}'.format(target)    
    if(int(hash,16) < int(target32,16)):
        print('###########BLOC MINED###################')
        print('HEADER=' + header_hex)
        print('HASH=' + hash)
        print('NONCE=' + str(inonc))
        print('NONCE (hex)=' + hex(inonc))
        print('###########BLOC MINED###################')

The output is :

1149 H/s
4405 H/s
4115 H/s
1534 H/s
3831 H/s
2392 H/s
4386 H/s
3165 H/s
###########BLOC MINED###################
NONCE (hex)=0xf4d81620
###########BLOC MINED###################

External link- bitcoin mining with python

Internal link – bitcoin algorithm python

Android SDK Exception in thread “main” java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema

When you try to lauchn the utility sdkmanager for android SDK you get the following error : Exception in thread “main” java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema

How to solve this error ?

Solution is to install JDK 8 :

brew cask uninstall java
brew tap homebrew/cask-versions
brew cask install java8
touch ~/.android/repositories.cfg
brew cask install android-sdk

In some case the right command is :

brew install openjdk@8

Install Android Command line tools

Little guide to setup android sdk from homebrew and install Android Command line tools

macOS(via Homebrew)

 brew install --cask android-sdk

Test the installation of android SDK

 sdkmanager --help

modules/speech_to_text/register_types.cpp:2:10: fatal error: ‘object_type_db.h’ file not found – GODOT Compilation

If you get this error modules/speech_to_text/register_types.cpp:2:10: fatal error: ‘object_type_db.h’ file not found you need to do this :

Introduction – modules/speech_to_text/register_types.cpp:2:10: fatal error: ‘object_type_db.h’ file not found

Go into directory source of GODOT and modules/speech_to_text :

File to open is register_types.cpp

You will see use of a header file

#include "object_type_db.h"

It changes between GODOT 2 and 3 from object_type_db.h to class_db.h

So chang it by :

#include "core/object/class_db.h"

Save and execute GODOT source compilation again it will works.

I get similar error on

modules/speech_to_text/stt_config.h:4:10: fatal error: ‘core/resource.h’ file not found

You need to open modules/speech_to_text/stt_config.h and modify :

#include "core/resource.h"

By :

#include "core/io/resource.h"

Also i get modules/speech_to_text/stt_error.h:4:10: fatal error: ‘core/object.h’ file not found

so i do the following in stt_error.h :

#include "core/object.h"
#include "core/ustring.h"
#include "core/object/object.h"
#include "core/string/ustring.h"

Internal links :

TypeError: can_build() takes 1 positional argument but 2 were given – Godot Compilation

If you get this type of errors TypeError: can_build() takes 1 positional argument but 2 were given when trying to compile Godot you have to do this :

When i tried to compile with scons i got this errors :

scons: Reading SConscript files ...
Automatically detected platform: osx
Building for macOS 10.12+, platform x86-64.
TypeError: can_build() takes 1 positional argument but 2 were given:
  File "/Users/myuser/godot/SConstruct", line 556:
    if config.can_build(env, selected_platform):

How to solve this error ?

First check you version of scons by launching :

scons -v

It will give you the scons path :

SCons path: ['/usr/local/Cellar/scons/4.1.0.post1/libexec/lib/python3.9/site-packages/SCons']

You then notice the use of python 3.9

You have to update your python to 3.9 :

Update Python easy update to Python 3.9 with homebrew – To update Mac os python from an older version to the latest python example python 3.9.1 you can do the folowing :

This article briefly describes how to replace its version of python on Mac. I wrote a similar article some time ago.

I used Homebrew to get the latest python as describe on

brew install python@3.9
python --version
Python 3.8.5
python3 --version
Python 3.8.5

You see that it stays on the older version.

Detect where python or python3 is setup

I had to first verify where my python command is pointing, by launching :

which python

It gave me in my case:


You need also to verify where is python3 command if you have different versions :

which python3  

I get :


Replace the version

I need to replace the version of the both command python and python3 by launching :

ln -s -f /usr/local/bin/python3.9 /Users/myuser/.pyenv/shims/python3

And also launch :

ln -s -f /usr/local/bin/python3.9 /Users/myuser/.pyenv/shims/python

The you can test it works :

python --version 
Python 3.9.1
python3 --version 
Python 3.9.1

Come back on GODOT compilation with Scons :

You need to localize the module that is bad in GODOT modules directory

For example i localize speech_to_text that was bad in

So i directly modify from this directory from can_build(env) to can_build(env, platform):

import os  # system()

def can_build(env, platform):
    if platform == "x11":
        has_pulse = os.system("pkg-config --exists libpulse-simple") == 0
        has_alsa = os.system("pkg-config --exists alsa") == 0
        return has_pulse or has_alsa
    elif platform in ["windows", "osx", "iphone", "android"]:
        return True
        return False

def configure(env):

And it works :

godot % scons
scons: Reading SConscript files ...
Automatically detected platform: osx
Building for macOS 10.12+, platform x86-64.
YASM is necessary for WebM SIMD optimizations.
WebM SIMD optimizations are disabled. Check if your CPU architecture, CPU bits or platform are supported!
Checking for C header file mntent.h... no
scons: done reading SConscript files.
scons: Building targets ...
[Initial build] Compiling ==> platform/osx/
[Initial build] Compiling ==> platform/osx/
[Initial build] Building RD_GLSL header: "servers/rendering/renderer_rd/shaders/canvas.glsl.gen.h"
[Initial build] Building RD_GLSL header: "servers/rendering/renderer_rd/shaders/canvas_occlusion.glsl.gen.h"
[Initial build] Building RD_GLSL header: "servers/rendering/renderer_rd/shaders/scene_forward.glsl.gen.h"
[Initial build] Building RD_GLSL header: "servers/rendering/renderer_rd/shaders/canvas_sdf.glsl.gen.h"

TypeError: can_build() takes 1 positional argument but 2 were given – Internal links :

This article briefly describes how to replace its version of python on Mac. I wrote a similar article some time ago.