What version of Go are you using (go version)?

golang.org/x/tools/gopls v0.6.6
    golang.org/x/tools/gopls@v0.6.6 h1:GmCsAKZMEb1BD1BTWnQrMyx4FmNThlEsmuFiJbLBXio=

go version go1.16 linux/amd64

What operating system and processor architecture are you using (go env)?

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/dima/.cache/go-build"
GOENV="/home/dima/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/dima/dvl/go/pkg/mod"
GONOPROXY="..."
GONOSUMDB=".."
GOOS="linux"
GOPATH="/home/dima/dvl/go"
GOPRIVATE="..."
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.16"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1594619228=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Clicked "Check for upgrade" lens in go.mod file

What did you expect to see?

Available upgrades

What did you see instead?

Error message Running the contributed command: '_vscode_delegate_cmd_klt93z4u' failed.

gopls server logs

[Error - 2:12:12 PM] Request workspace/executeCommand failed.
  Message: err: exit status 1: stderr: go list -m: can't determine available upgrades using the vendor directory
	(Use -mod=mod or -mod=readonly to bypass.)

  Code: 0 
[Error - 2:12:12 PM] 2021/03/03 14:12:12 command error: err: exit status 1: stderr: go list -m: can't determine available upgrades using the vendor directory
	(Use -mod=mod or -mod=readonly to bypass.)

Here is my VSCode settings for gopls

    "gopls": {
        // Add parameter placeholders when completing a function.
        "usePlaceholders": true,

        // If true, enable additional analyses with staticcheck.
        // Warning: This will significantly increase memory usage.
        // "staticcheck": true,
        "codelenses": {
            "generate": false,  // Don't run `go generate`.
            "gc_details": true  // Show a code lens toggling the display of gc's choices.
        },
    },

Shouldn't gopls run go list -m with -mod=readonly flag?