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"Could not launch Visual studio" error (on Mac)

I updated Visual Studio on Mac and after it tried to start, it told me I need to install Mono and directed me to a web page for that. I installed Mono. Now every time I launch Visual Studio, it just says
Could not launch Visual Studio
This application requires Xamarin.Mac native library side-by-side.
Please download and install the latest version of Mono.
I tried restarting but that didn't help.
What now?
(I'm running the latest macOS, and updated XCode if that matters. Mono is 5.4.0.201.)
New EDIT:(2022)
Users are saying there's a better way than uninstalling and reinstalling. I haven't tested it myself. See comments and answers for more information.
Previous EDIT:
Uninstalling and reinstalling is still the only way as the answer suggests, on: 2019:
March
July
August
September

The fastest and easiest way will be to uninstall and reinstall Visual Studio.

I have just ran into the same problem. I did follow the alert instructions and installed the newest mono framework from Mono websites (6.10.0). After this still the same issue. So I downloaded and ran VS4M installer and it said, it need version 6.8 of Mono framework and it did offer me to download and install this "update". So i went ahead. Still the same warning after launching VS.
Desperately enough after reading this thread I started looking for uninstall instructions (on official site). I did not want to use the script to auto-uninstall as I rather do it all by myself just for ensuring it will be everything done properly. So manual uninstall said to delete the Visual Studio app from /Application folder first. I did it. And woala: All the sudden the new app called "Visual Studio (old)" appeared (or maybe it was there already but I did not notice? Anyway, it was there). It was certainly weird, but I ran it. And it did work! Working instance of Visual Studio! I did check the updates and there was one for the app only. That was my first step straight after launching. It did download the new update and installed it correctly. Now I have end up with fully working and fully updated version of VS4M!
Conclusion:
Use VS4M installer to install all updates and necessarities to run VS4M. After this go to your /Application folder and delete "Visual Studio" app. The "Visual Studio (old)" app should appear. Run this app and update it straight away. (you might have to rename it afterwards from "Visual Studio (old)" to "Visual Studio")

Did you try going to the Applications folder? You'll see a Visual Studio.app file there and you can run Visual Studio by opening that.

I have sovled the problem by brew install --cask mono-mdk rather than brew install mono, in case anyone is installing mono through brew.

"C# 2017 compiler could not be created" error message while opening project

I've Visual Studio 2017 community edition. I have a C# project created using Visual Studio 2015. When I try to open the project in VS 2017 I get an error message prompt:
--------------------- Microsoft Visual Studio
Project 'dataStructureInCSharp' could not be opened because the Visual C# 2017 compiler could not be created.
Please re-install Visual Studio.
--------------------------- OK
I'm trying to obtain help if anyone else has faced similar issue. I feel going the uninstall and then reinstall route is very costly for me and would try that option last if I've got no other resort.
What I've done so far :
Tried starting visual studio with administrative privileges
But problem remained same.
I tried creating a new console project solution from scratch but in that case I get very same error and an additional error error also shown below:
System Environment: Windows 7 Ultimate Service Pack 1

You can try to close all VS 2017 instances and delete the folder %localappdata%\Microsoft\VisualStudio\15.0_xxxx\ComponentModelCache, then open VS to create a new Console project.
Or
please re-run the VS 2017 installer as administrator, click the icon beside ‘Launch’ button and choose ‘Repair’ to repair as shown below:

Just to brief the history of my problem, I had first installed Visual Studio(VS) 2017 community when it was in RC stage. This was first time when I saw the workload based UI of visual studio installation. Initially I simply chose .Net desktop development workload to get started as I was interested in creating only console applications to get my hands dirty.
Initially it was all working well. One fine day I added all other workloads I was interested in namely Universal Windows Platform Development, Azure Development, ASP.NET and web development,Node.js development, and Mobile development with .Net. I'm not sure if there any of the specific workloads to be blamed for the issue I've posted.
Just to avoid the case if RC and RTM release builds might not have messed up my entire environment, I simply uninstalled the entire stuff, rebooted my machine and installed it again from scratch from latest RTM release for Visual Studio Community.
I would strongly recommend that you first try possible solutions suggested by #Sara-MSFT before doing clean reinstall just in case if it works. It can save you couple of hours required in whole reinstallation process if it works.

No templates in Visual Studio 2017

After a Visual Studio 2017 (RC) installation from scratch, I can't find a standard list of templates. I'm specifically interested in the Console Application (C#) template and the Windows Form (C#) template. I'm pretty sure I'm missing one of the Individual Components. I'm not sure which one is supposed to be installed and I don't want to install all of them.
Please see my list with components installed.

You need to install it by launching the installer.
Click the "Workload" tab* in the upper-left, then check top right ".NET-Desktop Development" and hit install. Note it may modify your installation size (bottom-right), and you can install other Workloads, but you must install ".NET-Desktop Development" at least.
*as seen in comments below, users were not able to achieve the equivalent using the "Individual Components" tab.

If you have installed .NET desktop development and still you can't see the templates, then VS is probably getting the templates from your custom templates folder and not installed.
To fix that, copy the installed templates folder to custom.
This is your "installed" folder
C:\Program Files (x86)\Microsoft Visual Studio
14.0\Common7\IDE\ProjectTemplates
This is your "custom" folder
C:\Users[your username]\Documents\Visual
Studio\2017\Templates\ProjectTemplates
Typically this happens when you are at the office and you are running VS as an administrator and visual studio is confused how to merge both of them and if you notice they don't have the same folder structure and folder names.. One is CSHARP and the other C#....
I didn't have the same problem when I installed VS 2017 community edition at home though. This happened when I installed visual studio 2017 "enterprise" edition.

I found the path and wrote it in the options

My personal experience was that I had installed the Team Foundation Server client for 2017 first (was using it as a Proof of Concept for our QA team, while I was still using VS2015), then followed it up with Installing Visual Studio 2017 later to begin development.
What I ended up with on my Start Menu was a Visual Studio 2017 and a Visual Studio 2017 (2). The Visual Studio 2017 (2) had all the templates I was missing. Following the steps found in the First answer to this question (which were clear and easy to follow) did not fix my issue. I had thought that launching the client would upgrade to the Development Client, but it did not. I renamed it to Visual Studio Professional, and now have everything I need. Not sure if this happens to anyone else, but it was what happened to me, so I hope this helps someone.

NOTE: this topic is about installation issues with MS project templates.
I came here via a search in Google, I was looking for a missing Template option in Visual Studio 2017 File menu: in VS-2015, it was Export to Template and I used it to add my own standard Project Items.
Meanwhile, I found an answer.. my issue was not related to default templates and it does not need install things. The option Export to Template has been moved to the VS-2017 Project menu !

I had to reinstall .NET desktop development (throught Workload tab), even button was showing: Modify
After that Visual C# selection appeared :)
(And now i can use Console APP Template)

In my case, I had all of the required features, but I had installed the Team Explorer version (accidentally used the wrong installer) before installing Professional.
When running the Team Explorer version, only the Blank Solution option was available.
The Team Explorer EXE was located in:
"C:\Program Files (x86)\Microsoft Visual Studio\2017\TeamExplorer\Common7\IDE\devenv.exe"
Once I launched the correct EXE, Visual Studio started working as expected.
The Professional EXE was located in:
"C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\devenv.exe"

My C++ templates were there all along, it was my C# ones that were missing.
Similar to CSharpie, after trying many modify/re-installs, oddly the following finally worked for me :
- run the installer, but un-select 'Desktop development with C++'.
- allow installer to complete
- run the installer again, and select 'Desktop development with C++'.
- allow installer to complete

In my case, I had all of the required features, but I had installed the Team Explorer version (accidentally used the wrong installer) before installing Professional.
When running the Team Explorer version, only the Blank Solution option was available.
The Team Explorer EXE was located in: "C:\Program Files (x86)\Microsoft Visual Studio\2017\TeamExplorer\Common7\IDE\devenv.exe"
Once I launched the correct EXE, Visual Studio started working as expected.
The Professional EXE was located in: "C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\devenv.exe"
This solved my issue, and the reason was I had enterprise edition previously installed and then uninstalled and installed the professional edition. Team Explorer was not modified later when I moved to professional from enterprise edition.

Visual Studio, MonoGame integration issue

I installed monogame from there site, the 3.4 version for Visual Studio as it's the version specified for a course I'm taking. I already had the most recent version of Visual Studio 2015 community edition installed for use with unity. Something potentially important to note is that VS is installed on my (f) hardrive where as monogame autamtically installs onto the (C) boot drive where my windows is, I also installed windows SDK there. I don't have enough space on the boot drive for VS and Unity.
The install seemed to go fine, but no monogame templates show up within Visual studio itself when I try and crate a new project. I found them in the directory in documents, so they did install,(F:\Documents\Visual Studio 2015\Templates\ProjectTemplates\Visual C#\MonoGame) and nothing in itemtemplates, though copying it over to item templates didn't do anything. So, for some reason they aren't showing up in Visual Studio and they really need to in order to have any use.
Anyone have suggestions/solutions? I've reinstalled monogame multiple times and am very reluctant to reinstall VS.

I tried a number of things, including suggested solutions on these forums and nothing seemed to have any effect as nothing would appear under templates within VS. I finally just installed MonoGame 3.5 and it worked fine immediately... I've been doing the course with 3.5 and have ran into no problems so far, but admittedly I haven't gotten to the part which makes use of MonoGame yet....

This project(Visual Studio 2012 express) is incompatible with the current version of Visual Studio 2013 express

Am doing a back end project in C# in Visual Studio. My team mate had done it using Visual Studio 2012 express and everything seems to work there. But when i used git to clone it to my system where am using Visual Studio 2013 express, one part of the project says its incompatible with the current version of VS. I could clean and build the project, but was unable to run the project. I searched and found that one solution is to go to Programs and features, select VS, right click,select repair. But even after doing this, the problem persists. Is there any work around?

When I was learning ASP.NET MVC by Informit tutorials I was in the very similar situation. I downloaded the sample sources that was created in VS2013 but had VS2015 installed. It was some kind of bug \ magic, but VS didn't recognized some libraries in VS2015 even they were installed. What is more strange is the fact that when I decided to totally rewrite the project line by line it worked!
Of course, I tried to clean, rebuild, reinstall NuGet packages.
So, if you have an access to sources *.cs, then just try to create new project and copy-paste code.