Linux install

This is a quick installation guide on how to install KeePass 2 and the YAFD plugin.

Debian 9

sudo apt-get update
sudo apt-get install keepass2 mono-devel
sudo wget -O /usr/lib/keepass2/Plugins/YetAnotherFaviconDownloader.plgx "https://github.com/navossoc/KeePass-Yet-Another-Favicon-Downloader/releases/download/v1.2.0.0/YetAnotherFaviconDownloader.plgx"

Don't forget to update the link above to download the latest release available.

Mono

For best results, I strongly recommend that you upgrade the mono-devel package.

It is very easy to install, just follow the official instructions:

https://www.mono-project.com/download/stable/#download-lin-debian

When you are done, check if you are running the right version:

mono --version

It should output something like this:

Mono JIT compiler version 5.18.0.240 (tarball Wed Jan 16 09:10:58 UTC 2019)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           __thread
	SIGSEGV:       altstack
	Notifications: epoll
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	Interpreter:   yes
	LLVM:          yes(600)
	Suspend:       preemptive
	GC:            sgen (concurrent by default)

Troubleshooting SSL/TLS issues:

If you are having problems making HTTPS connections, try the following:

sudo apt update
sudo apt install ca-certificates ca-certificates-mono

cert-sync should run automatically when you install the official Mono packages, if it does not happen, trigger it manually with:

sudo cert-sync /etc/ssl/certs/ca-certificates.crt

More information is available on FAQ: Security