Laravel 'No application encryption key has been specified'

But... It has!

I'm frequently getting these messages now. Not on every page load, but on a page that might make a subsequent 8 - 10 HTTP calls, one or two of them are failing every time with the below error.

Tried clearing cache, view cache etc but even though I have an encryption key specified, it keeps popping up :(

[2018-08-05 19:10:34] production.ERROR: No application encryption key has been specified. {"exception":"[object] (RuntimeException(code: 0): No application encryption key has been specified. at D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Encryption\\EncryptionServiceProvider.php:42)
[stacktrace]
#0 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Support\\helpers.php(1041): Illuminate\\Encryption\\EncryptionServiceProvider->Illuminate\\Encryption\\{closure}(NULL)
#1 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Encryption\\EncryptionServiceProvider.php(46): tap(NULL, Object(Closure))
#2 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Encryption\\EncryptionServiceProvider.php(24): Illuminate\\Encryption\\EncryptionServiceProvider->key(Array)
#3 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(764): Illuminate\\Encryption\\EncryptionServiceProvider->Illuminate\\Encryption\\{closure}(Object(Illuminate\\Foundation\\Application), Array)
#4 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(646): Illuminate\\Container\\Container->build(Object(Closure))
#5 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(601): Illuminate\\Container\\Container->resolve('encrypter', Array)
#6 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Application.php(734): Illuminate\\Container\\Container->make('encrypter', Array)
#7 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(900): Illuminate\\Foundation\\Application->make('encrypter')
#8 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(828): Illuminate\\Container\\Container->resolveClass(Object(ReflectionParameter))
#9 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(795): Illuminate\\Container\\Container->resolveDependencies(Array)
#10 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(646): Illuminate\\Container\\Container->build('App\\\\Http\\\\Middle...')
#11 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Container\\Container.php(601): Illuminate\\Container\\Container->resolve('App\\\\Http\\\\Middle...', Array)
#12 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Application.php(734): Illuminate\\Container\\Container->make('App\\\\Http\\\\Middle...', Array)
#13 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Kernel.php(215): Illuminate\\Foundation\\Application->make('App\\\\Http\\\\Middle...')
#14 D:\\wamp64_www\\www\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Kernel.php(189): Illuminate\\Foundation\\Http\\Kernel->terminateMiddleware(Object(Illuminate\\Http\\Request), Object(Illuminate\\Http\\Response))
#15 D:\\wamp64_www\\www\\public\\index.php(60): Illuminate\\Foundation\\Http\\Kernel->terminate(Object(Illuminate\\Http\\Request), Object(Illuminate\\Http\\Response))
#16 {main}
"} 

via Chebli Mohamed