Monodevelop cannot load item type

Hey!

I am quite new in Unity and so far everything was really fine, but for a few hours I am dealing with a problem I cannot find a solution for.
I was workimg on a project, everything worked, I wrote my scripts with C# in MonoDevelop, and suddenly my pc needed to do some updates. After that, I wanted to continue working, starte unity and wanted to open a script, but instead of MonoDevelop, Visual Studio starts to load. After I cancel that, MonoDevelop opens, but shows the error I added a screenshot of.

-> Cannot load xyz.csproj with unknown item type {xyz}

I already reinstalled Unity several times, I set my preferred editor to MonoDevelop, both are the solutions I found in other forums. Nothings seems to help. I get that error in every project.

It would be really nice if somebody will help me, because my project is for uni and I do not have that much time left to deliver my project.

Thanks a lot!

Spoiler: Log file

INFO [2017-11-19 19:41:28Z]: Starting MonoDevelop-Unity 5.9.6
INFO [2017-11-19 19:41:28Z]: Running on Microsoft .NET 4.0.30319.42000
INFO [2017-11-19 19:41:28Z]: Found GTK# version 2.12.26
INFO [2017-11-19 19:41:28Z]: Using GTK+ 2.24.22
INFO [2017-11-19 19:41:28Z]: Add-in loaded: MonoDevelop.Core
INFO [2017-11-19 19:41:28Z]: Add-in loaded: MonoDevelop.Ide
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.WindowsPlatform
INFO [2017-11-19 19:41:29Z]: Initializing Runtime MS.NET
Starting MonoDevelop-Unity
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.Debugger
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.SourceEditor2
INFO [2017-11-19 19:41:29Z]: Add-in loaded: Unity.Utilities
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.UnityScript
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.DesignerSupport
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.Refactoring
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.CSharpBinding
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.Boo
INFO [2017-11-19 19:41:29Z]: Add-in loaded: MonoDevelop.VersionControl
INFO [2017-11-19 19:41:30Z]: Add-in loaded: MonoDevelop.Debugger.Soft
INFO [2017-11-19 19:41:30Z]: Add-in loaded: MonoDevelop.Debugger.Soft.Unity
INFO [2017-11-19 19:41:30Z]: Add-in loaded: MonoDevelop.Xml
INFO [2017-11-19 19:41:30Z]: Add-in loaded: MonoDevelop.NUnit
Loading Workbench
INFO [2017-11-19 19:41:30Z]: Add-in loaded: MonoDevelop.DocFood
INFO [2017-11-19 19:41:30Z]: Add-in loaded: MonoDevelop.AssemblyBrowser
INFO [2017-11-19 19:41:30Z]: Add-in loaded: MonoDevelop.RegexToolkit
Initializing Main Window
INFO [2017-11-19 19:41:30Z]: Creating DefaultWorkbench
INFO [2017-11-19 19:41:31Z]: Add-in loaded: MonoDevelop.ILAsmBinding
ERROR [2017-11-19 19:41:31Z]: Monodoc documentation tree could not be loaded.
System.IO.FileNotFoundException: Die Datei "C:\Users\Sophia\Documents\Studienprojekt\monodoc.xml" konnte nicht gefunden werden.
Dateiname: "C:\Users\Sophia\Documents\Studienprojekt\monodoc.xml"
bei System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
bei System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
bei System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize)
bei System.Xml.XmlDownloadManager.GetStream(Uri uri, ICredentials credentials, IWebProxy proxy, RequestCachePolicy cachePolicy)
bei System.Xml.XmlUrlResolver.GetEntity(Uri absoluteUri, String role, Type ofObjectToReturn)
bei System.Xml.XmlTextReaderImpl.OpenUrlDelegate(Object xmlResolver)
bei System.Threading.CompressedStack.runTryCode(Object userData)
bei System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
bei System.Threading.CompressedStack.Run(CompressedStack compressedStack, ContextCallback callback, Object state)
bei System.Xml.XmlTextReaderImpl.OpenUrl()
bei System.Xml.XmlTextReaderImpl.Read()
bei System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace)
bei System.Xml.XmlDocument.Load(XmlReader reader)
bei System.Xml.XmlDocument.Load(String filename)
bei Monodoc.RootTree.LoadTree(String basedir)
bei Monodoc.RootTree.LoadTree()
bei MonoDevelop.Projects.HelpService.InitializeHelpTree() in c:\buildslave\monoDevNGExAddin\monodevelop\main\src\core\MonoDevelop.Core\MonoDevelop.Projects\HelpService.cs:Zeile 77.
WARNING [2017-11-19 19:41:31Z]: Could not load project 'Studienprojekt.Plugins.csproj' with unknown item type '{E097FAD1-6243-4DAD-9C02-E9B9EFC3FFC1}'
WARNING [2017-11-19 19:41:31Z]: Could not load project 'Studienprojekt.csproj' with unknown item type '{E097FAD1-6243-4DAD-9C02-E9B9EFC3FFC1}'
WARNING [2017-11-19 19:41:31Z]: Could not load project 'Studienprojekt.Editor.Plugins.csproj' with unknown item type '{E097FAD1-6243-4DAD-9C02-E9B9EFC3FFC1}'
INFO [2017-11-19 19:41:31Z]: Add-in loaded: MonoDevelop.HexEditor
ERROR [2017-11-19 19:41:32Z]: Error launching player connection discovery service: Unity player discovery will be unavailable
System.Net.Sockets.SocketException (0x80004005): Beim Aufruf von getsockopt oder setsockopt wurde eine nicht unterstützte Option bzw. Ebene angegeben
bei System.Net.Sockets.Socket.setMulticastOption(SocketOptionName optionName, MulticastOption MR)
bei System.Net.Sockets.Socket.SetSocketOption(SocketOptionLevel optionLevel, SocketOptionName optionName, Object optionValue)
bei MonoDevelop.Debugger.Soft.Unity.PlayerConnection..ctor()
bei MonoDevelop.Debugger.Soft.Unity.UnitySoftDebuggerEngine..cctor()
WARNING [2017-11-19 19:41:32Z]: Failed to load: C:\Program Files\Unity\Editor\Data\PlaybackEngines\iOSSupport\Data\iosdevices.csv
System.IO.DirectoryNotFoundException: Ein Teil des Pfades "C:\Program Files\Unity\Editor\Data\PlaybackEngines\iOSSupport\Data\iosdevices.csv" konnte nicht gefunden werden.
bei System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
bei System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
bei System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
bei System.IO.StreamReader..ctor(String path, Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize, Boolean checkHost)
bei System.IO.StreamReader..ctor(String path, Encoding encoding)
bei System.IO.File.InternalReadAllLines(String path, Encoding encoding)
bei System.IO.File.ReadAllLines(String path)
bei MonoDevelop.Debugger.Soft.Unity.iOSDevices.LoadDescriptions(String path)
bei MonoDevelop.Debugger.Soft.Unity.iOSDevices.SetupDescriptions(String path)
WARNING [2017-11-19 19:41:32Z]: Error while initializing usbmuxd
System.IO.FileNotFoundException: C:\Program Files\Unity\Editor\Data\PlaybackEngines\iOSSupport\x86\UnityEditor.iOS.Extensions.Native.dll
bei MonoDevelop.Debugger.Soft.Unity.WindowsDllLoader.MonoDevelop.Debugger.Soft.Unity.IDllLoader.LoadLibrary(String fileName)
bei MonoDevelop.Debugger.Soft.Unity.Usbmuxd.LoadDll(String nativeDll)
bei MonoDevelop.Debugger.Soft.Unity.Usbmuxd.Setup(String dllPath)
bei MonoDevelop.Debugger.Soft.Unity.iOSDevices.SetupDll(String path)

 

Sounds like your project files are corrupt. Delete the .sln file and all the .csproj files in your project's root folder. These files are autogenerated by Unity, so it's safe to delete them, but if they get into a bad state, they can prevent you from opening the project

 

Honestly, switch to Visual Studios. I generally have nothing but trouble with monodevelop. I had nothing but issues with monodevelop back in the day when I first started with Unity. You should let Visual Studios open it and see if you still get some error, if not, it's probably just another monodevelop behavior.

You can also do what @Baste says, but honestly, for your sanity, make the switch to VS or anything else.

 

Thank you both, I will try Bastes solution first and then see if I can handle Visual Studio

 

I have the exact same problem and nothing I did worked and it does the same with vs2017. I switched to mono to test and it did the same thing with all my projects. The code still works in the editor, a new build work too and you can still connect unity to notepad++ to edit the code without any issues.