As of Notepad++ v7.6.3 from January 2019, the old Plugin Manager plugin is obsolete. Notepad++ ships with it’s own Plugins Admin in the Plugins menu, which handles installing plugins.

If you try to install a plugin with the old Plugin Manager in v7.6.3 or later, it will
likely not install the plugin in the right directory, and the plugin will not be visible to Notepad++. Further, as of 2022, there are reports that the old Plugin Manager cannot download its plugin list.

The original FAQ entry has been kept for historical purposes (and anyone intentionally trying to use Notepad++ v7.5 - v7.6.2)

This FAQ has been marked as “Retired” and moved to the “Blogs” section.

- from your friendly neighborhood moderator

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Starting from notepad++ version 7.5 the plugin manager does not come bundled anymore.
Here you can see why this was decided.

But this doesn’t mean it cannot be used anymore.

Download the latest versions from here,
unzip it to the same directory where the notepad++ executable is and
start notepad++ - done.

It should be noted that there is a need that plugin manager and notepad++
must use the same architecture, means
PluginManager_vX.X.X_x64.zip for notepad++ 64bit and
PluginManager_vX.X.X_UNI.zip for 32bit version of notepad++.

To find out which notepad++ version is in use, see menu ?->About Notepad++ or press F1

The instructions for doing a manual install, which explains where to put the files after you download the zip, can be found at https://htmlpreview.github.io/?https://github.com/bruderstein/nppPluginManager/blob/master/doc/index.html#install