Question Issues with running code in Rider and long enter play mode times

Hello everyone, i have few issues with unity which I will list here:

1. First one is when I'm running the code in JetBrains Rider (I don't know if it's related to Jetbrains Rider or this csproj file):
Invalid option ‘8.0’ for /langversion; must be ISO-1, ISO-2, 3, 4, 5 or Default

I tried changing it to something like latest but Unity switches it back to 8.0 and the issue persists

2. Long play mode times after I do any edit of my c# script. These long enter play mode times will persist unless i restart the unity. I have the enter play mode box ticked in editor settings. I don't have this problem when I'm doing visual scripting. First load might be longer but then it just works instantly. In c# on the other hand it will stay like that untill I restart which is annoying. I'm talking about multiple play modes that take long after one edit, not just play mode that freezes or something.

3. Another issue I have that JetBrains Rider somehow don't detect the integration between it and Unity although I have package installed from the package manager. Raider asks me to change editor in external tools which I did and wants me to install the package which I have.

I would like someone to help me with these issues. I was learning Unity with visual scripting but want to switch to c#. And these are the issues I have right now. The first two are the most crucial I would like to fix. I tried looking these problems on the internet but didn't find anything in particular.

Using the newest unity version : Unity 2021.1.7

I have to add that I'm running Windows and I didn't have any of these issues on linux which is kinda weird. But Windows is my daily driver

 

Although I fixed it by going to the LTS version all of the problems went away. But why was all of this happening on the newest one? I even tried reinstalling it.

 

For anyone who winds up here in the future, this was the solution that worked for me for the

invalid /langversion

issue:

Despite the error message claiming that it is related to the

/langversion

, and

csproj

files, the actual solution was to change the MSBuild version from

Auto detected (4.0)

to

16.0

(I used the embedded JetBrains path).



Remember not to just hit

Save

, and instead hit the dropdown arrow and save it to the correct layers, which probably means

team-shared

:

 

This helped me thank you. I wasn't even using rider at the time my I needed to renew my subscription but I was having the same issue no matter what editor I was using.

 

This is it, finally, after some misleading posts. Thank you

 

ive started having this same / similar issue after a fresh install of unity and rider./

Invalid option '9.0' for /langversion; must be ISO-1, ISO-2, 3, 4, 5 or Default

no solution so far. The above work around is not fully resolving the problem.

 

Same this for some years now.