You must build the *OmniSharp Server* before using this layer's features.
After all plugins installed, *cd* to the directory `$SPACEVIM_PLUGIN_BUNDLE_DIR/repos/github.com/OmniSharp/omnisharp-vim/server` (by default `$HOME/.cache/vimfiles/repos/github.com/OmniSharp/omnisharp-vim/server`, and then run
```
xbuild
```
for macOS and linux, or
```
msbuild
```
for Windows.
For more information, please read this [link](https://github.com/OmniSharp/omnisharp-vim#installation).