ipylab Ipylab returns empty list of commands. Console shows error Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module

I use JupyterLab 3.2.3 and installed ipylab 0.5.2 using pip.

Following notebook code


from ipylab import JupyterFrontEnd

app = JupyterFrontEnd()
commands = app.commands.list_commands()
commands

returns an empty array.

The Chrome dev tools console contains the error

Module ipylab, semver range ^0.5.2 is not registered as a widget module

Full output:

react_devtools_backend.js:4045 Could not instantiate widget
overrideMethod @ react_devtools_backend.js:4045
(anonymous) @ manager-base.js:274
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
rejected @ manager-base.js:18
Promise.then (async)
step @ manager-base.js:19
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Error: Could not create a model.
    at promiseRejection (utils.js:119)
    at async _handleCommOpen (523.fa256ee012d38a89b65a.js:1)
    at async KernelConnection._handleCommOpen (default.js:1038)
    at async KernelConnection._handleMessage (default.js:1206)
overrideMethod @ react_devtools_backend.js:4045
promiseRejection @ utils.js:119
Promise.catch (async)
ManagerBase.handle_comm_open @ manager-base.js:150
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Exception opening new comm
overrideMethod @ react_devtools_backend.js:4045
_handleCommOpen @ default.js:1044
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Could not instantiate widget
overrideMethod @ react_devtools_backend.js:4045
(anonymous) @ manager-base.js:274
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
rejected @ manager-base.js:18
Promise.then (async)
step @ manager-base.js:19
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Error: Could not create a model.
    at promiseRejection (utils.js:119)
    at async _handleCommOpen (523.fa256ee012d38a89b65a.js:1)
    at async KernelConnection._handleCommOpen (default.js:1038)
    at async KernelConnection._handleMessage (default.js:1206)
overrideMethod @ react_devtools_backend.js:4045
promiseRejection @ utils.js:119
Promise.catch (async)
ManagerBase.handle_comm_open @ manager-base.js:150
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Exception opening new comm
overrideMethod @ react_devtools_backend.js:4045
_handleCommOpen @ default.js:1044
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Could not instantiate widget
overrideMethod @ react_devtools_backend.js:4045
(anonymous) @ manager-base.js:274
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
rejected @ manager-base.js:18
Promise.then (async)
step @ manager-base.js:19
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Error: Could not create a model.
    at promiseRejection (utils.js:119)
    at async _handleCommOpen (523.fa256ee012d38a89b65a.js:1)
    at async KernelConnection._handleCommOpen (default.js:1038)
    at async KernelConnection._handleMessage (default.js:1206)
overrideMethod @ react_devtools_backend.js:4045
promiseRejection @ utils.js:119
Promise.catch (async)
ManagerBase.handle_comm_open @ manager-base.js:150
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Exception opening new comm
overrideMethod @ react_devtools_backend.js:4045
_handleCommOpen @ default.js:1044
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Could not instantiate widget
overrideMethod @ react_devtools_backend.js:4045
(anonymous) @ manager-base.js:274
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
rejected @ manager-base.js:18
Promise.then (async)
step @ manager-base.js:19
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Error: Could not create a model.
    at promiseRejection (utils.js:119)
    at async _handleCommOpen (523.fa256ee012d38a89b65a.js:1)
    at async KernelConnection._handleCommOpen (default.js:1038)
    at async KernelConnection._handleMessage (default.js:1206)
overrideMethod @ react_devtools_backend.js:4045
promiseRejection @ utils.js:119
Promise.catch (async)
ManagerBase.handle_comm_open @ manager-base.js:150
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
react_devtools_backend.js:4045 Exception opening new comm
overrideMethod @ react_devtools_backend.js:4045
_handleCommOpen @ default.js:1044
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)
loadClass @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:264
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
Promise.then (async)
ManagerBase.register_model @ manager-base.js:209
register_model @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:249
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)
loadClass @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:264
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
Promise.then (async)
register_model @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:249
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)
loadClass @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:264
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
Promise.then (async)
ManagerBase.register_model @ manager-base.js:209
register_model @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:249
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)
loadClass @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:264
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
Promise.then (async)
register_model @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:249
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)
loadClass @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:264
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
Promise.then (async)
ManagerBase.register_model @ manager-base.js:209
register_model @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:249
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)
loadClass @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:264
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
Promise.then (async)
register_model @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:249
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)
loadClass @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:264
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase._make_model @ manager-base.js:258
(anonymous) @ manager-base.js:247
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
Promise.then (async)
ManagerBase.register_model @ manager-base.js:209
register_model @ 523.fa256ee012d38a89b65a.js:1
(anonymous) @ manager-base.js:249
step @ manager-base.js:45
(anonymous) @ manager-base.js:26
(anonymous) @ manager-base.js:20
__awaiter @ manager-base.js:16
ManagerBase.new_model @ manager-base.js:233
ManagerBase.handle_comm_open @ manager-base.js:145
_handleCommOpen @ 523.fa256ee012d38a89b65a.js:1
_handleCommOpen @ default.js:1038
async function (async)
_handleCommOpen @ default.js:1037
_handleMessage @ default.js:1206
async function (async)
_handleMessage @ default.js:1168
(anonymous) @ default.js:110
Promise.then (async)
KernelConnection._onWSMessage @ default.js:107
523.fa256ee012d38a89b65a.js:1 Uncaught (in promise) Error: Module ipylab, semver range ^0.5.2 is not registered as a widget module
    at x.loadClass (523.fa256ee012d38a89b65a.js:1)
    at x.<anonymous> (manager-base.js:264)
    at step (manager-base.js:45)
    at Object.next (manager-base.js:26)
    at manager-base.js:20
    at new Promise (<anonymous>)
    at __awaiter (manager-base.js:16)
    at x.ManagerBase._make_model (manager-base.js:258)
    at x.<anonymous> (manager-base.js:247)
    at step (manager-base.js:45)

Dec 20 '21 13:12 stefaneidelloth

Updating JupyterLab to version 3.2.5 did not help. List of commands is still empty. The errors from the Chrome dev tools vanished.

Dec 20 '21 13:12 stefaneidelloth

I think that the output of jupyter server extension list, jupyter serverextension list and jupyter labextension list might be relevant.

Dec 20 '21 17:12 krassowski

jupyter server extension list:

Config dir: C:\Users\eis\.jupyter

C:\python_env\App\WinPython\python-3.9.4.amd64\lib\site-packages\jupyter_server\transutils.py:13: FutureWarning: The alias `_()` will be deprecated. Use `_i18n()` inste
ad.
  warnings.warn(warn_msg, FutureWarning)
Config dir: C:\python_env\App\WinPython\python-3.9.4.amd64\etc\jupyter
    dask_labextension enabled
    - Validating dask_labextension...
      dask_labextension 5.0.1 ok
    jupyter_lsp enabled
    - Validating jupyter_lsp...
      jupyter_lsp 1.1.4 ok
    jupyter_server_proxy enabled
    - Validating jupyter_server_proxy...
      jupyter_server_proxy  ok
    jupyter_server_mathjax enabled
    - Validating jupyter_server_mathjax...
      jupyter_server_mathjax  ok
    jupyterlab enabled
    - Validating jupyterlab...
      jupyterlab 3.2.5 ok
    jupyterlab_git enabled
    - Validating jupyterlab_git...
      jupyterlab_git 0.30.0 ok
    nbclassic enabled
    - Validating nbclassic...
      nbclassic  ok
    nbdime enabled
    - Validating nbdime...
      nbdime 3.0.0 ok
    voila-gridstack.server_extension enabled
    - Validating voila-gridstack.server_extension...
      voila-gridstack.server_extension  ok
    voila.server_extension enabled
    - Validating voila.server_extension...
      voila.server_extension  ok

Config dir: C:\ProgramData\jupyter

jupyter serverextension list:

config dir: C:\Users\eis\.jupyter
    jupyter_nbextensions_configurator disabled
    - Validating...
Error loading server extension jupyter_nbextensions_configurator
      X is jupyter_nbextensions_configurator importable?
config dir: C:\python_env\App\WinPython\python-3.9.4.amd64\etc\jupyter
    dask_labextension enabled
    - Validating...
      dask_labextension 5.0.1 ok
    jupyter_lsp enabled
    - Validating...
C:\python_env\App\WinPython\python-3.9.4.amd64\lib\site-packages\jupyter_server\transutils.py:13: FutureWarning: The alias `_()` will be deprecated. Use `_i18n()` inste
ad.
  warnings.warn(warn_msg, FutureWarning)
      jupyter_lsp 1.1.4 ok
    jupyter_server_proxy enabled
    - Validating...
      jupyter_server_proxy  ok
    jupyterlab enabled
    - Validating...
      jupyterlab 3.2.5 ok
    jupyterlab_git enabled
    - Validating...
      jupyterlab_git 0.30.0 ok
    nbdime enabled
    - Validating...
      nbdime 3.0.0 ok
    panel enabled
    - Validating...
      X is panel importable?
    voila-gridstack.server_extension enabled
    - Validating...
      voila-gridstack.server_extension  ok
    voila.server_extension enabled
    - Validating...
      voila.server_extension  ok
    voila enabled
    - Validating...
      voila 0.2.9 ok
config dir: C:\ProgramData\jupyter
    jupyter_nbextensions_configurator enabled
    - Validating...
Error loading server extension jupyter_nbextensions_configurator
      X is jupyter_nbextensions_configurator importable?

jupyter labextension list:

JupyterLab v3.2.5
C:\python_env\App\WinPython\python-3.9.4.amd64\share\jupyter\labextensions
        bqplot v0.5.26 enabled ok (python, bqplot)
        dask-labextension v5.0.1 enabled ok (python, dask_labextension)
        ipycanvas v0.8.2 enabled ok
        ipylab v0.5.2 enabled ok (python, ipylab)
        jupyter-leaflet v0.13.5 enabled ok
        jupyter-matplotlib v0.9.0 enabled ok
        nbdime-jupyterlab v2.1.0 enabled ok
        @bokeh/jupyter_bokeh v3.0.0 enabled ok (python, jupyter_bokeh)
        @jupyter-widgets/jupyterlab-manager v3.0.0 enabled ok (python, jupyterlab_widgets)
        @jupyterlab/git v0.30.0 enabled ok (python, jupyterlab-git)
        @jupyterlab/server-proxy v3.0.2 enabled ok
        @krassowski/jupyterlab-lsp v3.5.0 enabled ok (python, jupyterlab_lsp)
        @pyviz/jupyterlab_pyviz v2.0.1 enabled ok (python, pyviz_comms)
        @voila-dashboards/jupyterlab-gridstack v0.2.0 enabled ok (python, voila-gridstack)
        @voila-dashboards/jupyterlab-preview v2.0.2 enabled ok (python, voila)

Other labextensions (built into JupyterLab)
   app dir: C:\Users\eis\AppData\Roaming\Python\share\jupyter\lab
        @treezjs/workspace_module v0.0.4 enabled ok

Dec 21 '21 08:12 stefaneidelloth

In order to resolve the error on jupyter_nbextensions_configurator, I installed it with

pip install jupyter_nbextensions_configurator
jupyter nbextensions_configurator enable --user

As expected, that did not seem to influence the ipylab issue.

jupyter serverextension list:

config dir: C:\Users\eis\.jupyter
    jupyter_nbextensions_configurator enabled
    - Validating...
      jupyter_nbextensions_configurator 0.4.1 ok
config dir: C:\python_env\App\WinPython\python-3.9.4.amd64\etc\jupyter
    dask_labextension enabled
    - Validating...
      dask_labextension 5.0.1 ok
    jupyter_lsp enabled
    - Validating...
C:\python_env\App\WinPython\python-3.9.4.amd64\lib\site-packages\jupyter_server\transutils.py:13: FutureWarning: The alias `_()` will be deprecated. Use `_i18n()` inste
ad.
  warnings.warn(warn_msg, FutureWarning)
      jupyter_lsp 1.1.4 ok
    jupyter_server_proxy enabled
    - Validating...
      jupyter_server_proxy  ok
    jupyterlab enabled
    - Validating...
      jupyterlab 3.2.5 ok
    jupyterlab_git enabled
    - Validating...
      jupyterlab_git 0.30.0 ok
    nbdime enabled
    - Validating...
      nbdime 3.0.0 ok
    panel enabled
    - Validating...
      X is panel importable?
    voila-gridstack.server_extension enabled
    - Validating...
      voila-gridstack.server_extension  ok
    voila.server_extension enabled
    - Validating...
      voila.server_extension  ok
    voila enabled
    - Validating...
      voila 0.2.9 ok
config dir: C:\ProgramData\jupyter
    jupyter_nbextensions_configurator enabled
    - Validating...
      jupyter_nbextensions_configurator 0.4.1 ok

Dec 21 '21 08:12 stefaneidelloth

I tried app.commands.execute('docmanager:save') again.

That does work now.

app.commands.list_commands()

still returns an empty list.

Dec 21 '21 09:12 stefaneidelloth

If I wait a few seconds and enter

app.commands._command_list

in an extra cell, it returns a list of commands. Might be some timing / initialization issue. I tried to wait for some seconds in the code but that did not help:

Manual cell execution gives

Dec 21 '21 09:12 stefaneidelloth

Might be some timing / initialization issue. I tried to wait for some seconds in the code but that did not help:

Right that's probably the case yes. Since retrieving the list of commands requires a round trip to the frontend.

There is a ready event that could be useful here: https://github.com/jtpio/ipylab/blob/main/examples/commands.ipynb

Dec 23 '21 11:12 jtpio