JupyterLab 1.x to 2.x Extension Migration Guide

This is a migration guide for updating extensions that support JupyterLab 1.x to work in JupyterLab 2.x. We will look at two examples of extensions that cover most of the APIs that extension authors might be using:

Upgrading library versions

The @phosphor/* libraries that JupyterLab 1.x uses have been renamed to @lumino/*. Updating your package.json is straightforward. The easiest way to do this is to look in the JupyterLab core packages code base and to simply adopt the versions of the relevant libraries that are used there.

Updating the debugger extension’s libraries in package.json

Updating the shortcuts UI extension’s libraries in package.json


In these examples, note that we are using the 2.0.0-beta.x version of many libraries. This was to test the extensions against the JupyterLab 2.0 beta release before the final version. For the final release, your package.json should depend on version ^2.0.0 of these packages.

Migrating from @phosphor to @lumino

The foundational packages used by JupyterLab are now all prefixed with the NPM namespace @lumino instead of @phosphor. The APIs for these packages have not changed. The @phosphor namespaced imports need to be updated to the new @lumino namespaced packages:

Update from @phosphor/... to @lumino/...
@phosphor/application @lumino/application
@phosphor/collections @lumino/collections
@phosphor/commands @lumino/commands
@phosphor/coreutils @lumino/coreutils
@phosphor/datagrid @lumino/datagrid
@phosphor/datastore @lumino/datastore
@phosphor/default-theme @lumino/default-theme
@phosphor/disposable @lumino/disposable
@phosphor/domutils @lumino/domutils
@phosphor/dragdrop @lumino/dragdrop
@phosphor/keyboard @lumino/keyboard
@phosphor/messaging @lumino/messaging
@phosphor/properties @lumino/properties
@phosphor/signaling @lumino/signaling
@phosphor/virtualdom @lumino/virtualdom
@phosphor/widgets @lumino/widgets


p- prefixed CSS classes, data-p- attributes and p- DOM events are deprecated. They will continue to work until the next major release of Lumino.

  • .p- CSS classes such as .p-Widget should be updated to .lm-, e.g. .lm-Widget
  • data-p- attributes such as data-p-dragscroll should be updated to data-lm-, e.g. data-lm-dragscroll
  • p- DOM events such as p-dragenter should be updated to lm-, e.g. lm-dragenter

Updating former @jupyterlab/coreutils imports

JupyterLab 2.0 introduces several new packages with classes and tokens that have been moved out of @jupyterlab/coreutils into their own packages. These exports have been moved.


It might be helpful to delete node_modules and yarn.lock when updating these libraries.

Export Package
DataConnector @jupyterlab/statedb
Debouncer @lumino/polling
DefaultSchemaValidator @jupyterlab/settingregistry
IDataConnector @jupyterlab/statedb
IObjectPool @jupyterlab/statedb
IPoll @lumino/polling
IRateLimiter @lumino/polling
IRestorable @jupyterlab/statedb
IRestorer @jupyterlab/statedb
ISchemaValidator @jupyterlab/settingregistry
ISettingRegistry @jupyterlab/settingregistry
IStateDB @jupyterlab/statedb
nbformat @jupyterlab/nbformat
Poll @lumino/polling
RateLimiter @lumino/polling
RestorablePool @jupyterlab/statedb
SettingRegistry @jupyterlab/settingregistry
Settings @jupyterlab/settingregistry
StateDB @jupyterlab/statedb
Throttler @lumino/polling

Using Session and SessionContext to manage kernel sessions


For full API documentation and examples of how to use @jupyterlab/services, consult the repository.

ConsolePanel and NotebookPanel now expose a sessionContext: ISessionContext attribute that allows for a uniform way to interact with kernel sessions.

Any widget that matches the interface IDocumentWidget has a context: DocumentRegistry.IContext attribute with a sessionContext: ISessionContext attribute.

For example, consider how the @jupyterlab/debugger extension’s DebuggerService updated its isAvailable() method.


await kernel.ready is no longer necessary before the kernel connection kernel can be used. Kernel messages will be buffered as needed while a kernel connection is coming online, so you should be able to use a kernel connection immediately. If you want to retrieve the kernel info (or if for some other reason you want to wait until at least one message has returned from a new kernel connection), you can do await kernel.info.

Using the new icon system and LabIcon


For full API documentation and examples of how to use the new icon support based on LabIcon from @jupyterlab/ui-components, consult the repository.