'protoc-gen-go-grpc: program not found or is not executable', despite all the efforts

I'm trying to run makefile command 'gen' from this project https://github.com/penthaapatel/grpcblog. The command is: protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=. --go-grpc_opt=paths=source_relative blog/blog.proto However I get an error:

protoc-gen-go-grpc: program not found or is not executable --go-grpc_out: protoc-gen-go-grpc: Plugin failed with status code 1. make: *** [/home/deckard/go/src/grpcblog/Makefile:2: gen] Error 1 

I use Ubuntu 20.04? Golang-1.13.8 with $GOROOT=/usr/lib/go-1.13 and $GOPATH=/home/deckard/go ($HOME is /home/deckard). Protoc is libprotoc v.3.6.1.. I installed protobuf-compiler both with:

sudo apt install protobuf-compiler 

and

go get -u github.com/golang/protobuf/{proto,protoc-gen-go} 

There's a folder /home/deckard/go/src/github.com/golang/protobuf and /home/deckard/go/src/google.golang.org/protobuf with /home/deckard/go/src/google.golang.org/protobuf, with, I guess, everything i need. My bashrc configurations (tried few methods, so things overlap each other):

export GOROOT=/usr/lib/go-1.13 export GOPATH=$HOME/go export GOBIN=$GOPATH/bin export PATH=$PATH:$GOROOT:$GOPATH:$GOBIN export PATH=$PATH:$GOPATH/bin export GO_PATH=~/go export PATH=$PATH:/$GO_PATH/bin 

So i tried solutions from here: protoc-gen-go: program not found or is not executable, but none of them helped me. Any clue would be helpful, because I stuck and am very tired.

UPDATE: ls -l /home/deckard/go/bin/protoc-gen-go-grpc shows rwxrwxr-x 1 deckard deckard 7970222 мая 1 14:55 /home/deckard/go/bin/protoc-gen-go-grpc, and printenv PATH returns /home/deckard/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/deckard/.dotnet/tools:/usr/lib/go-1.13:/home/deckard/go:/home/deckard/go/bin:/home/deckard/go/bin://home/deckard/go/bin

UPDATE: which protoc returns /usr/bin/protoc (tried to install it from precompiled binary to /home/deckard/.local/bin/protoc, didn't helped). In both cases protoc-gen-go-grpc --version returns protoc-gen-go-grpc 1.1.0. I also tried to copy everything from google.golang.org/protobuf to google.golang.org/protobuf, no result.