# Extension Manager doen not show any extension

**URL:** <https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457>\
**Category:** Support\
**Tags:** extensions-manager\
**Created:** [September 1, 2021, 10:55am UTC](https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457 "2021-09-01T10:55:40Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ylcnkzy](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ylcnkzy/32/12189_2.png) [@ylcnkzy](https://discourse.slicer.org/u/ylcnkzy)\
**Post date:** [September 1, 2021, 10:55am UTC](https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457/1 "2021-09-01T10:55:40Z")

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It seems like there is a problem with the extension manager. There is no extension seen at the extension manager. I thought it might be specific to me, but then I realized that there is an update on the software. For the one who has such issue and benefits from the link below ([how to install extensions manually](https://discourse.slicer.org/t/downloading-extensions-for-older-releases/19256?layout=empty&os=win&arch=amd64&revision=29738));

Best,

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**Author:** ![John\_Agapito](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/john_agapito/32/12206_2.png) [@John\_Agapito](https://discourse.slicer.org/u/John_Agapito)\
**Post date:** [September 1, 2021, 1:50pm UTC](https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457/2 "2021-09-01T13:50:12Z")

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I am having the same problem - and even when I try to install the extension (SlicerRT) manually, it installs but then does not activate in the menus…running version 4.11.20210226.

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**Author:** ![ylcnkzy](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ylcnkzy/32/12189_2.png) [@ylcnkzy](https://discourse.slicer.org/u/ylcnkzy)\
**Post date:** [September 1, 2021, 2:05pm UTC](https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457/3 "2021-09-01T14:05:58Z")

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Hi John,  
After you install the extension (such as SlicerRT), you need to restart the 3D slicer. In general, it asks you to restart the software with an notification (located right bottom of the extension manager).

Best,

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**Author:** ![John\_Agapito](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/john_agapito/32/12206_2.png) [@John\_Agapito](https://discourse.slicer.org/u/John_Agapito)\
**Post date:** [September 1, 2021, 2:18pm UTC](https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457/4 "2021-09-01T14:18:03Z")

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Yes, I know that is what is supposed to happen, but it does not: the restart button stays greyed-out. The error log shows: Uncaught ReferenceError: midas is not defined

Even if I restart the application anyway, the situation persists: SlicerRT appears in the “manage extensions” tab, but does not function - does not appear in the menus…

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**Author:** ![mikebind](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@mikebind](https://discourse.slicer.org/u/mikebind)\
**Post date:** [September 1, 2021, 10:07pm UTC](https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457/5 "2021-09-01T22:07:54Z")

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This is due to a temporary issue related to the extension manager server being upgraded. The workaround process is described here:

> [@Downloading extensions for older releases](https://discourse.slicer.org/t/downloading-extensions-for-older-releases/19256):
>
> Due to the recent transition to the updated Extension Manager and Data Store infrastructure, when using Slicer-4.11 (or older) version, users will need to manually download and install extensions from the new extension server, and download data sets from an alternative server instead of using the Data Store module. Rationale for the transition can be found [here](https://discourse.slicer.org/t/upcoming-downtime-for-download-slicer-org-and-extension-manager-due-to-package-server-transition/17444). We anticipate that this will be a temporary measure will the transition is finalized. Thank you for your patience! Please do not hes…

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [September 3, 2021, 1:26am UTC](https://discourse.slicer.org/t/extension-manager-doen-not-show-any-extension/19457/6 "2021-09-03T01:26:38Z")

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The simplest solution is to use the Slicer Preview Release. The Extensions manager has no issues in this version and it should generally work better than the latest Slicer Stable Release.