How can i update the version of my GHC for my stack project? ERROR: ghcide compiled by GHC 8.10 failed to load packages:haskell-language-server-8.10.7

Question

I have created a stack haskell project a few months ago and finished it then. I wanted to add and fix a few issues it has, but when i tried opening the .hs file on vs code (visual studio code) i got the error in the title, the full one is at the bottom of this question. I tried reinstalling stack, but nothing changed. I also updated the stack.yaml resolver to the newest lts build, which is 19.9 using the resolver: url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/19/9.yaml The error appears to be that my project is using an older version of ghc that my machine doesn't have, especially since the folder C:\cabal\store\ghc-8.10.7 doesn't exist on my machine, where this is the only one that exists in that path C:\cabal\store\ghc-9.2.1 So my question is, how can i update the version of my GHC for my specific stack project?

The full error: ghcide compiled by GHC 8.10 failed to load packages: haskell-language-server-8.10.7~1.7.0.0.exe: can't find a package database at C:\cabal\store\ghc-8.10.7\package.db. Please ensure that ghcide is compiled with the same GHC installation as the project.

Stack version: 2.7.5

GHCi/GHC version: 8.10.7

IDE: VS code (visual studio code)

Answer 1

Tl;dr If you want to change the version of ghc(i) when you use ghci then use ghcup set ghc (version number). if you want to change it on stack, the use stack config set resolver ghc-(version number). Remaking the stack project also helpt me, so maybe try that as well if you are stuck.

This was a hell of a rollercoaster to fix but i finally fixed it. To clarify i think the issue was that i had more than one version of ghc(i), but those different versions were also installed in different ways, for example i have 8.10.7 version on stack, and the 9.2.3 version on cabal, it didn't help i also didn't have the 8.10 ghc(i) version. As you can already tell it was confusing for the compiler as much as it was confusing for me. I tried deleting them and reinstalling different versions, but none of them worked, even after i made sure i added them to path. By not working i mean when iw rite ghc or ghci command on terminal they are not recongised. I went back to have the two versions i had (8.10.7 and 9.2.3). I then used the command ghcup set ghc 9.2.3 to set the main ghc version to 9.2.3, now i was able to use the commands ghc and ghci again. the command stack ghci worked, but it only worked outside of my stack project, so i had to remake the project for it work. I also changed the stack ghc(i) version to the latest version by using stack config set resolver ghc-9.2.3, but then i changed this one back to 9.0.2 as it is the last version that stack recommends.