PHP: 7.2
Laravel: 5.7

Some requests failed with below error(Http 500- Server error), while other requests along the same request are successful. Passport is used to authenticate api request. api auth middleware is used.

production.ERROR: No application encryption key has been specified. {"exception":"[object] (RuntimeException(code: 0): No application encryption key has been specified. at F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Encryption\EncryptionServiceProvider.php:42)
[stacktrace]
#0 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Support\helpers.php(1041): Illuminate\Encryption\EncryptionServiceProvider->Illuminate\Encryption\{closure}(NULL)
#1 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Encryption\EncryptionServiceProvider.php(46): tap(NULL, Object(Closure))
#2 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Encryption\EncryptionServiceProvider.php(24): Illuminate\Encryption\EncryptionServiceProvider->key(Array)
#3 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Container\Container.php(764): Illuminate\Encryption\EncryptionServiceProvider->Illuminate\Encryption\{closure}(Object(Illuminate\Foundation\Application), Array)
#4 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Container\Container.php(646): Illuminate\Container\Container->build(Object(Closure))
#5 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Container\Container.php(601): Illuminate\Container\Container->resolve('encrypter', Array)
#6 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Application.php(734): Illuminate\Container\Container->make('encrypter', Array)
#7 F:\wamp64\www\service\vendor\laravel\passport\src\PassportServiceProvider.php(271): Illuminate\Foundation\Application->make('encrypter')
#8 [internal function]: Laravel\Passport\PassportServiceProvider->Laravel\Passport\{closure}(Object(Illuminate\Http\Request), NULL)
#9 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Auth\RequestGuard.php(58): call_user_func(Object(Closure), Object(Illuminate\Http\Request), NULL)
#10 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Auth\GuardHelpers.php(60): Illuminate\Auth\RequestGuard->user()
#11 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Auth\Middleware\Authenticate.php(61): Illuminate\Auth\RequestGuard->check()
#12 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Auth\Middleware\Authenticate.php(41): Illuminate\Auth\Middleware\Authenticate->authenticate(Array)
#13 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Illuminate\Auth\Middleware\Authenticate->handle(Object(Illuminate\Http\Request), Object(Closure), 'api')
#14 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#15 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Middleware\ThrottleRequests.php(57): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#16 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Illuminate\Routing\Middleware\ThrottleRequests->handle(Object(Illuminate\Http\Request), Object(Closure), 120, '1')
#17 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#18 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(104): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#19 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Router.php(667): Illuminate\Pipeline\Pipeline->then(Object(Closure))
#20 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Router.php(642): Illuminate\Routing\Router->runRouteWithinStack(Object(Illuminate\Routing\Route), Object(Illuminate\Http\Request))
#21 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Router.php(608): Illuminate\Routing\Router->runRoute(Object(Illuminate\Http\Request), Object(Illuminate\Routing\Route))
#22 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Router.php(597): Illuminate\Routing\Router->dispatchToRoute(Object(Illuminate\Http\Request))
#23 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Http\Kernel.php(176): Illuminate\Routing\Router->dispatch(Object(Illuminate\Http\Request))
#24 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(30): Illuminate\Foundation\Http\Kernel->Illuminate\Foundation\Http\{closure}(Object(Illuminate\Http\Request))
#25 F:\wamp64\www\service\vendor\spatie\laravel-cors\src\Cors.php(28): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#26 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Spatie\Cors\Cors->handle(Object(Illuminate\Http\Request), Object(Closure))
#27 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#28 F:\wamp64\www\service\vendor\fideloper\proxy\src\TrustProxies.php(57): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#29 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Fideloper\Proxy\TrustProxies->handle(Object(Illuminate\Http\Request), Object(Closure))
#30 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#31 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Http\Middleware\TransformsRequest.php(31): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#32 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Illuminate\Foundation\Http\Middleware\TransformsRequest->handle(Object(Illuminate\Http\Request), Object(Closure))
#33 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#34 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Http\Middleware\TransformsRequest.php(31): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#35 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Illuminate\Foundation\Http\Middleware\TransformsRequest->handle(Object(Illuminate\Http\Request), Object(Closure))
#36 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#37 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Http\Middleware\ValidatePostSize.php(27): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#38 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Illuminate\Foundation\Http\Middleware\ValidatePostSize->handle(Object(Illuminate\Http\Request), Object(Closure))
#39 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#40 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode.php(62): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#41 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(151): Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode->handle(Object(Illuminate\Http\Request), Object(Closure))
#42 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Routing\Pipeline.php(53): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}(Object(Illuminate\Http\Request))
#43 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Pipeline\Pipeline.php(104): Illuminate\Routing\Pipeline->Illuminate\Routing\{closure}(Object(Illuminate\Http\Request))
#44 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Http\Kernel.php(151): Illuminate\Pipeline\Pipeline->then(Object(Closure))
#45 F:\wamp64\www\service\vendor\laravel\framework\src\Illuminate\Foundation\Http\Kernel.php(116): Illuminate\Foundation\Http\Kernel->sendRequestThroughRouter(Object(Illuminate\Http\Request))
#46 F:\wamp64\www\service\public\index.php(55): Illuminate\Foundation\Http\Kernel->handle(Object(Illuminate\Http\Request))
#47 {main}
"}