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  • Changes in WebExtension APIs
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  1. Add-on Development
  2. Add-on Update Guides

Update for Thunderbird 91

Required steps to update add-ons for Thunderbird 91.

PreviousAdapt to Changes in Thunderbird 92-102NextAdapt to Changes in Thunderbird 79-91

Last updated 8 months ago

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Support for legacy extensions was removed from Thunderbird Beta version 74, released in February 2020. Since Thunderbird 78 only modern are supported. This section only covers the required update steps for add-ons which are already compatible with Thunderbird 78 and need to be made compatible with Thunderbird 91.

Changes in WebExtension APIs

Our WebExtension APIs are meant to be stable, but we are adding new features and since this is a very young technology this might also require backward incompatible changes. All WebExtension API changes are listed in our API documentation:

Changes in Thunderbird Core

Changes in Shared Experiments

If you are using any of the shared Experiments, you probably do not have to update them on your own. Check if an updated version is already available:

MailExtensions can still run legacy code inside . Such legacy code has to be adjusted to changes made in Thunderbird Core. All known changes are listed in the following document:

If you have encountered a change which is not yet listed there, please , so we can update the list.

MailExtensions
Thunderbird 81
Thunderbird 82
Thunderbird 83
Thunderbird 84
Thunderbird 85
Thunderbird 86
Thunderbird 87
Thunderbird 88
Thunderbird 89
Thunderbird 90
Thunderbird 91
Changes in Thunderbird 79-91
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Experiments
Shared Experiments on DTN