What causes "no goroutine selected" in go-delve/delve?

Select a goroutine first: use 'goroutine ' in the terminal or SetCurrentGoroutine / scope.GoroutineID via the API

no goroutine selected

Error message

no goroutine selected

What it means

errNoGoroutine is returned by EvalExpressionWithCalls when no goroutine is currently selected as the scope for the injected call. Function-call injection needs a specific goroutine context to run the call on, and none is set.

Source

Thrown at pkg/proc/fncall.go:62

//  - evalop.CallInjectionSetTarget
//  - evalCallInjectionCopyArg
//  - evalCallInjectionComplete
//
// When the target has runtime.debugPinner then evalCallInjectionPinPointer
// must be also called in a loop until it returns false.

const (
	debugCallFunctionNamePrefix1 = "debugCall"
	debugCallFunctionNamePrefix2 = "runtime.debugCall"
	maxDebugCallVersion          = 2
	maxArgFrameSize              = 65535
)

var (
	errFuncCallUnsupported        = errors.New("function calls not supported by this version of Go")
	errFuncCallUnsupportedBackend = errors.New("backend does not support function calls")
	errFuncCallInProgress         = errors.New("cannot call function while another function call is already in progress")
	errNoGoroutine                = errors.New("no goroutine selected")
	errGoroutineNotRunning        = errors.New("selected goroutine not running")
	errNotEnoughStack             = errors.New("not enough stack space")
	errTooManyArguments           = errors.New("too many arguments")
	errNotEnoughArguments         = errors.New("not enough arguments")
	errNotAGoFunction             = errors.New("not a Go function")
	errFuncCallNotAllowedStrAlloc = errors.New("literal string can not be allocated because function calls are not allowed without using 'call'")
)

type functionCallState struct {
	// savedRegs contains the saved registers
	savedRegs Registers
	// err contains a saved error
	err error
	// expr is the expression being evaluated
	expr *ast.CallExpr
	// fn is the function that is being called
	fn *Function
	// receiver is the receiver argument for the function

View on GitHub (pinned to a23773e6c3)

Solutions

Select a goroutine first: use 'goroutine <id>' in the terminal or SetCurrentGoroutine / scope.GoroutineID via the API
List goroutines with 'goroutines' and pick a runnable (Running) one
Retry the call after the goroutine scope is established

Example fix

// before
dlv> call foo(1)        // no goroutine selected
// after
dlv> goroutine 1
dlv> call foo(1)

Defensive patterns

Strategy: validation

Validate before calling

// ensure a goroutine is selected before calling
dlv> goroutines
dlv> goroutine <id>
dlv> call foo(1)

Try / catch

if errors.Is(err, proc.ErrNoGoroutine) {
    // select the current goroutine (API: scope with GoroutineID set) and retry
}

Prevention

Always run 'goroutine <id>' (or set GoroutineID in the eval scope) before 'call'
In RPC clients, populate EvalScope.GoroutineID explicitly
Pick a goroutine from the 'goroutines' listing rather than assuming a default

When it happens

Trigger: Calling EvalExpressionWithCalls without a current goroutine selected (no 'goroutine N' / SetCurrentGoroutine beforehand); evaluating in a scope where the selected thread has no associated goroutine; API clients omitting the goroutine ID.

Common situations: Fresh RPC sessions where the client never selected a goroutine; scripts that switch threads but not goroutines; evaluations issued while the target is in a state without a current goroutine.

Related errors

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/669db08c7edfe27a. Report an issue: GitHub.