XML Tools for Notepad++: libXML and/or libXSLT missing

I tried some of the answers that Mr. Hooper linked, and also did not have success. After a whole lot of see-if-this-fix-works, I ended up completely uninstalling without saving any settings, grabbed the absolute latest installer (7.6.2 - 32bit), and installed it. Then, using the built-in Plugins Admin, I installed XML Tools, and it worked!

It should be noted that Notepad++ 7.5.8 (32 bit) with XML Tools 2.4.9 (manually installed) DID work as well. I still don't have an answer as to what's causing the problem, which is the frustrating part, but I THINK it might have something to do with an update process vs. uninstall and reinstall.

I had an issue with XML Tools failing to install via the Plugins Admin even when reinstalling the latest version of NPP (currently 7.7.1).

It turned out that a corporate firewall was blocking the Plugins Admin from accessing the repository. Unfortunately, there is no notification in the UI for this which is causing a very frustrating experience of nothing happening.

It took me a while and some Googling to figure out how to manually install the latest version of XML Tools (2.4.11) with Notepad++ higher than v7.6:

• please download xmltools manually from here: https://github.com/morbac/xmltools/releases/download/2.4.11.0/Xml.Tools.2.4.11.0.x86.Unicode.zip

• extract Xml.Tools.2.4.11.0.x86.Unicode.zip anywhere to a temporary
  location

• create a folder XMLTools inside of Detination Folder*

• copy the files XMLTools.dll and change.log as well as the whole folder libs from the extracted Xml.Tools.2.4.11.0.x86.Unicode folder to: {Detination Folder*}\XMLTools

• restart notepad++ (only necessary if it was opened while copying the xmltools plugin to it’s folder destination)

Destination Folder:

• %ProgramFiles%\Notepad++\plugins\ (32 bit OS)
• %ProgramFiles(x86)%\Notepad++\plugins\ (64 bit OS, 32 bit Npp)
• %ProgramFiles%\Notepad++\plugins\ (64 bit OS, 64 bit Npp)

Source: https://notepad-plus-plus.org/community/topic/16983/xml-tools/11

Try with new default plugin manager

I still had the OLD plugin manager inside NPPx86.

A while back there was a bit of drama in the NPP project and the old plugin manager got kicked out of NPP in version 7.5 on 2017-08-16. (Archived here.)

So, back then, if you wanted to have any plugin manager at all then you had to manually insert the old plugin manager into NPP yourself. And that's what I did.

But now NPP seems to bring its own NEW plugin manager.

So I uninstalled NPP, deleted %ProgramFiles(x86)%\Notepad++ and deleted %appdata%\Notepad++. And then did a reinstall using "Notepad++ Installer 32-bit x86" (npp.7.6.6.Installer.exe).

Then via Plugins | Plugins Admin...

I was successfully able to install XML Tools.

So fresh install did the trick for me. (But if you're hesitant you might first try to throw out the old plugin manager manually somehow before you reinstall.)