MonoDevelop error CS0103 - Now fixed.

I was working away in Unity, when all of the sudden MonoDevelop-Unity started highlighting the "UnityEngine" in the using declaration, and everything in the UnityEngine package in the file in pink, with the error:

"Error CS01013: The name 'UnityEngine' does not exist in the current context."

Any idea what broke, and how I can fix it?
I've searched this forum and the unity-answers site to no avail.

 

I should have mentioned: my code also builds and runs fine.

Also, in the "Assemby-CSharp" part of the "Solution" in MonoDevelop, "UnityEngine" is present and doesn't show any errors.

I'm really at a loss here.

 

This is fixed now.

I noticed when I rebuilt the project in MonoDevelop that it was complaining about an "xmlns" element that shouldn't be in the file named "..". When I tried to click on the error it told me ".. is a directory". -- Correctly so.

On a hunch, I checked the project folder (in Windows) and found there were two .csproj files; one named after my project -- last dated the exact time I started experiencing this problem -- and another named "Assembly-CSharp.csproj" which was dated today/now. So I assume Unity had created a new default project file and switched to that one on that date, and that started giving me the weird error.

THE FIX:
I simply deleted the file named "Assembly-CSharp.csproj", restarted Unity, it created a new "Assembly-CSharp.csproj" file, and when I opened MonoDevelop everything works now.

 

FYI, I think what causes this is editing the Project > Assembly-CSharp options, and changing the Source Code > Code Formatting rules.

 

Thank you, I was looking everywhere for why this was happening.

 

This might be old, but thank you for sharing. This really helpful.

 

I think running the Microsoft .NET Framework Repair Tool worked for me.
https://www.microsoft.com/en-us/download/confirmation.aspx?id=30135

 

On my side it came from ZoneAlarm that did not have access to Internet. i remove the restriction and everything went back to normal

 

Hey there, sorry to resurrect an old thread, but I couldn't find a solution to this and stumbled accross one myself. So if anyone finds this thread...

I deleted my "Assembly-CSharp" files in my project directory, and reloaded my project. I then right clicked on the CSharp.csproj and opened it with monodevelop. That gave me an error, surprisingly, but I opened it again from monodevelop's recent files and it said that it loaded the solution. After that, this problem went away.

 

In Mono Develop;

Project > Assembly-CSharp Options > Build > General > Target Framework > Mono/.NET 4.5

 

If i click on project, Assembly CSharp Options is not an option for me

 

For anyone that ends up here looking for an answer.
I had the same issue and discovered the antivirus had blocked MonoDevelop.exe Once solved, everything went back to normal.

 

Thank you all! This worked for me too.

 

Found this error after installation of new windows. This problem is due to the target framework that the monodevelop uses to find the required libraries and framework. The solution is
1) Install the .NET frame work.
or go to the following location in the monodevelop and see if there are any .NET frame work available,if so select one. If there are more than one then select other and check. This work for me.
Project --> Assembly-CSharp Options --> Build --> General --> Target Framework --> Mono/.NET 4.0.

 

In Mono Develop;

Project > Assembly-CSharp Options > Build > General > Target Framework > Mono/.NET 4.5

@orix_ Thanks its work for me

 

thank you