Добавьте его 1 раз в самом низу.
ReactDOM.render(
<Router history={browserHistory}>
<Route path="/" component={Layout}>
<Route path="/sing" component={SignUp}/>
<Route path="/profile" component={Profile} />
<Route path="/register_approve" component={Validation} />
<Route path="/forgot_password" component={ForgotPassword} />
<Route path="/confirm_email" component={ConfirmEmail} />
<Route path="/restore_password/:token" component={RestorePassword} />
<Route path="/confirm_invite" component={ConfirmInvite} />
<Route path="/my-cabinet" component={Cabinet} />
<Route path="/members" component={Members} />
<Route path="/invite-member" component={InviteMember} />
<Route path="/not_access" component={NotAccess} />
<Route path="/finance" component={Finance}>
<Route path="/finance/project" component={FinanceProject}/>
<Route path="/finance/fixed-costs" component={FinanceFixedCost}/>
<Route path="/finance/fixed-costs" component={FinanceFixedCost}/>
<Route path="/finance/salary" component={FinanceSalary}/>
<Route path="/finance/other" component={FinanceOther}/>
</Route>
</Route>
<Route path="*" component={NotFound} />
</Router>,
document.getElementById('root')
