DIY Fix for Reconnect Bug
TL;DR - your anti-virus is likely using techniques employed by tools used by hackers/cheaters. The anti-virus solutions stop bad things from happening, and the tools hackers use allow them to attempt to manipulate the game, any data it uses, and/or attack players or even Rito themselves. Hence the new anti-cheat functionality picks up on these techniques and stops you from playing the game. Skip to solution below.
Having not played for 2 days, I booted up and logged in. Everytime I joined a game, all would go well until the champion select had finished. At which point the loading screen never appeared and I was presented with the "Reconnect" option, as though I'd disconnected and was trying to re-enter the game. Google-fu revealed that people have been hitting this issue for years, and recent posts on this forum reflected that. Then I read about the Rito's new anti-cheat changes.
Note that I've tried putting this in terms that most people can understand, so for you neck beards out there; forgive me. Disclaimer: I'm not a big exploit dev/reverse engineer so feel free to get your nerd on in the comments.
Basically, Riot doesn't want people using software that can interact or interfere with the client or game processes ("LeagueClient.exe" and "Leage of Legends.exe" respectively). This affects you the same way it affected me, as I'm pretty paranoid by nature, so I run Host Based Intrustion Detection System (HIPS) software on my home rig, specifically SpyShelter (https://www.spyshelter.com/ - I heard even Alex Jones uses it). However if you use an anti-virus product, you likely do too!
In short, HIPS solutions monitor system activity and (normally by default) use a pre-defined set of rules to recognise suspicious system behavior. When this type of activity is identified, the HIPS solution stops the offending program or process from carrying out the activity. It does this by monitoring calls to the Windows API (the thing provided by Windows that lets software run on your computer). By doing this (and running with high privileges/admin) it can see all activities carried out by processes (e.g. registry key changes, network communications, monitoring keyboard input etc.). I chose SpyShelter because it's mainly a HIPS solution and it doesn't really try and do anything ridiulously fancy. It prompts me to make a decision about everything it picks up. However, a lot of Anti-Virus/malware/spyware/[buzzword for bad stuff here] will come with some form of HIPS, and not all of them will be clear about it, nor will they be clear about what it does or how it works. They might even do things automagically without tell you about it, which I guess is kinda good if you're not savy or Alex Jones.
Anyway, it turns out that if I wanted to find exploits or ways of cheating in League, I'd use tools that employ the same techniques to put me in a position to manipulate League during runtime. The logic being that if I can see what is going on under the hood, I might be to abuse it to do illegal things in the game, or worse, attack other players or Rito themselves (que X-Files theme tune). Riot obviously don't want this, so they implemented anti-cheat stuff that in turn detects the use of such tools, and incorrectly detects anti-virus solutions as being potentially malicious tools. The game then kills itself (or refuses to run) to prevent or make it harder to abuse.
Solution Firstly, most anti-virus solutions have exclusion options. Exclude the installation folder (C:\Riot Games\League of Legends by default) in anti-virus product. Even better, if you can excldue specific processes/executable files (.exe), exclude the the "LeagueClient.exe" and "League of Legends.exe" files. The former can be found in the installation directory shown above, and the latter can be found in the installation folder in the folder "\RADS\solutions\lol_game_client_sln\releases\0.0.1.227\deploy". It's worth mentioning at this point that there is another "League of Legends.exe" file that you should probably exclude in the folder "\RADS\projects\lol_game_client\releases\0.0.1.168\deploy". I'm not 100% certain which League of Legends.exe file is used but I guess the first one. Now try going into a practice game and seeing if you get past champion select.
If that doesn't work, see if you can disable HIPS features in your anti-virus. You might have to do some Googling to find out whether you even have that option. I'd recommend turning any disabled features back on when your done crushing bronze plebs.
Lastly, if you're desperate, uninstall your anti-virus product. Likelihood is you're on Windows (RIP Linux players) meaning you still have Windows Defender. It's not the best but it's actually alright, just start thinking about what you download/click on.
Be Cool If you find that you unistalled something or disabled HIPS features etc. in whatever software you had installed fixes this issue, post the name of the software in the original thread regarding anti-cheat changes and help Rito out. I didn't post this in the thread because I thought it would get burried under the Hypervisor and Linux people (RIP). You can find it here:
The more people do it, the less people have this problem, and the sooner you can go back to your anti-virus (hopefully, assuming Rito's plan is to whitelist known non-malicious software in future).