Failure after PHP 8 Upgrade

[Dual-0]

I am running Firefly III version 5.4.6

I have upgraded to PHP 8 on a non-Docker Installation
I got this failure when going to budget overview

[2021-02-08 10:52:12] local.ERROR: Class "NumberFormatter" not found {"userId":2,"exception":"[object] (Error(code: 0): Class \"NumberFormatter\" not found at /var/www/firefly-iii/app/Support/Amount.php:201)
[stacktrace]
#0 /var/www/firefly-iii/app/Support/Amount.php(179): FireflyIII\\Support\\Amount->formatFlat()
#1 /var/www/firefly-iii/app/Support/Twig/AmountFormat.php(134): FireflyIII\\Support\\Amount->formatAnything()
#2 /var/www/firefly-iii/storage/framework/views/twig/d0/d07bde025a0de4f9c61e4b2ddd8a0685cb4afd5674699202cc7b32cf06c87b6b.php(205): FireflyIII\\Support\\Twig\\AmountFormat::FireflyIII\\Support\\Twig\\{closure}()
#3 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(405): __TwigTemplate_63e3f1d84b5e1bd39c23277beb1778a0819700795d459fdd39b822cf83124dc2->doDisplay()
#4 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(378): Twig\\Template->displayWithErrorHandling()
#5 /var/www/firefly-iii/vendor/rcrowe/twigbridge/src/Twig/Template.php(41): Twig\\Template->display()
#6 /var/www/firefly-iii/storage/framework/views/twig/d9/d9b83bf68024bef1cfe6076f1632e6ff8a9be402ea1449380de3f190779bb03c.php(198): TwigBridge\\Twig\\Template->display()
#7 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(182): __TwigTemplate_af6a755a95b41cd9fb13d1ab29fd30daa43e5e41837605064a9dc1a74d64cfe2->block_content()
#8 /var/www/firefly-iii/storage/framework/views/twig/ba/ba06e82fc82ef4ffa00c349eb70e17a45acbbffccbd5d5db0637bb9359732336.php(291): Twig\\Template->displayBlock()
#9 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(405): __TwigTemplate_53cf85c501de0b4de2a7aca7f127d2bab130532d54d231cd4ef4da7b69e8069c->doDisplay()
#10 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(378): Twig\\Template->displayWithErrorHandling()
#11 /var/www/firefly-iii/vendor/rcrowe/twigbridge/src/Twig/Template.php(41): Twig\\Template->display()
#12 /var/www/firefly-iii/storage/framework/views/twig/d9/d9b83bf68024bef1cfe6076f1632e6ff8a9be402ea1449380de3f190779bb03c.php(45): TwigBridge\\Twig\\Template->display()
#13 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(405): __TwigTemplate_af6a755a95b41cd9fb13d1ab29fd30daa43e5e41837605064a9dc1a74d64cfe2->doDisplay()
#14 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(378): Twig\\Template->displayWithErrorHandling()
#15 /var/www/firefly-iii/vendor/rcrowe/twigbridge/src/Twig/Template.php(41): Twig\\Template->display()
#16 /var/www/firefly-iii/vendor/twig/twig/src/Template.php(390): TwigBridge\\Twig\\Template->display()
#17 /var/www/firefly-iii/vendor/rcrowe/twigbridge/src/Engine/Twig.php(92): Twig\\Template->render()
#18 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/View/View.php(139): TwigBridge\\Engine\\Twig->get()
#19 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/View/View.php(122): Illuminate\\View\\View->getContents()
#20 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/View/View.php(91): Illuminate\\View\\View->renderContents()
#21 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Http/Response.php(62): Illuminate\\View\\View->render()
#22 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Http/Response.php(34): Illuminate\\Http\\Response->setContent()
#23 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(765): Illuminate\\Http\\Response->__construct()
#24 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(737): Illuminate\\Routing\\Router::toResponse()
#25 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(691): Illuminate\\Routing\\Router->prepareResponse()
#26 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(128): Illuminate\\Routing\\Router->Illuminate\\Routing\\{closure}()
#27 /var/www/firefly-iii/app/Http/Middleware/Installer.php(81): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#28 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\Installer->handle()
#29 /var/www/firefly-iii/app/Http/Controllers/Controller.php(115): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#30 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(149): FireflyIII\\Http\\Controllers\\Controller->FireflyIII\\Http\\Controllers\\{closure}()
#31 /var/www/firefly-iii/app/Http/Middleware/InterestingMessage.php(58): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#32 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\InterestingMessage->handle()
#33 /var/www/firefly-iii/app/Http/Middleware/Binder.php(79): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#34 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\Binder->handle()
#35 /var/www/firefly-iii/app/Http/Middleware/Range.php(61): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#36 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\Range->handle()
#37 /var/www/firefly-iii/vendor/jc5/google2fa-laravel/src/Middleware.php(29): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#38 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): PragmaRX\\Google2FALaravel\\Middleware->handle()
#39 /var/www/firefly-iii/app/Http/Middleware/Authenticate.php(74): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#40 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\Authenticate->handle()
#41 /var/www/firefly-iii/vendor/laravel/passport/src/Http/Middleware/CreateFreshApiToken.php(50): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#42 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Laravel\\Passport\\Http\\Middleware\\CreateFreshApiToken->handle()
#43 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Session/Middleware/AuthenticateSession.php(58): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#44 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Session\\Middleware\\AuthenticateSession->handle()
#45 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/VerifyCsrfToken.php(77): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#46 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\VerifyCsrfToken->handle()
#47 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/View/Middleware/ShareErrorsFromSession.php(49): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#48 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\View\\Middleware\\ShareErrorsFromSession->handle()
#49 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Session/Middleware/StartSession.php(121): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#50 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Session/Middleware/StartSession.php(63): Illuminate\\Session\\Middleware\\StartSession->handleStatefulRequest()
#51 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Session\\Middleware\\StartSession->handle()
#52 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Cookie/Middleware/AddQueuedCookiesToResponse.php(37): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#53 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Cookie\\Middleware\\AddQueuedCookiesToResponse->handle()
#54 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Cookie/Middleware/EncryptCookies.php(67): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#55 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Cookie\\Middleware\\EncryptCookies->handle()
#56 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(103): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#57 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(693): Illuminate\\Pipeline\\Pipeline->then()
#58 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(668): Illuminate\\Routing\\Router->runRouteWithinStack()
#59 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(634): Illuminate\\Routing\\Router->runRoute()
#60 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(623): Illuminate\\Routing\\Router->dispatchToRoute()
#61 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(166): Illuminate\\Routing\\Router->dispatch()
#62 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(128): Illuminate\\Foundation\\Http\\Kernel->Illuminate\\Foundation\\Http\\{closure}()
#63 /var/www/firefly-iii/app/Http/Middleware/InstallationId.php(53): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#64 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\InstallationId->handle()
#65 /var/www/firefly-iii/vendor/fideloper/proxy/src/TrustProxies.php(57): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#66 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Fideloper\\Proxy\\TrustProxies->handle()
#67 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#68 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest->handle()
#69 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#70 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest->handle()
#71 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/ValidatePostSize.php(27): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#72 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\ValidatePostSize->handle()
#73 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/PreventRequestsDuringMaintenance.php(87): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#74 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\PreventRequestsDuringMaintenance->handle()
#75 /var/www/firefly-iii/app/Http/Middleware/SecureHeaders.php(51): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#76 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\SecureHeaders->handle()
#77 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(103): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#78 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(141): Illuminate\\Pipeline\\Pipeline->then()
#79 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(110): Illuminate\\Foundation\\Http\\Kernel->sendRequestThroughRouter()
#80 /var/www/firefly-iii/public/index.php(76): Illuminate\\Foundation\\Http\\Kernel->handle()
#81 {main}
"}

Information from Debug Site:

Debug information generated at 2021-02-08 11:56:50 Europe/Berlin for Firefly III version **5.4.6**.

| Scope | Version |
| --- | --- |
| Firefly III | 5.4.6 |
| Firefly III API | 1.4.0 |
| PHP | 8.0.2 |
| Host | Linux |

| System info | Value |
| --- | --- |
| Installation ID | a49d7b93-4da9-4a92-8bb4-fad91d87b0f6 |
| Using docker? | false |
| Telemetry | false |
| Layout | v1 |
| App environment | local |
| App debug mode | false |
| App cache driver | file |
| App logging | notice, stack |
| Display errors | Off |
| Error reporting | ALL errors |
| Interface | fpm-fcgi |
| Default language | de_DE |
| Default locale | equal |
| BCscale | 12 |
| DB drivers | pgsql |
| Current driver | pgsql |
| DB version | 15 (exp. 15) |
| Login provider | eloquent  |
| Trusted proxies (.env) |  |

| User info | Value |
| --- | --- |
| Session start | 2021-02-01 00:00:00 |
| Session end | 2021-02-28 23:59:59 |
| Session first | 2021-01-01 00:00:00 |
| User ID | 1 |
| User language | de_DE |
| User locale | de_DE |
| Attempt at "de_DE.utf8" | 'de_DE.utf8' |
| Attempt at "de_DE.UTF-8" | 'de_DE.UTF-8' |
| User agent | Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.151 Safari/537.36 |

More Debug Informations:

Truncated from this point <----|k/src/Illuminate/Pipeline/Pipeline.php(149): FireflyIII\\Http\\Controllers\\Budget\\IndexController->FireflyIII\\Http\\Controllers\\Budget\\{closure}()
#26 /var/www/firefly-iii/app/Http/Controllers/Controller.php(115): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#27 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(149): FireflyIII\\Http\\Controllers\\Controller->FireflyIII\\Http\\Controllers\\{closure}()
#28 /var/www/firefly-iii/app/Http/Middleware/InterestingMessage.php(58): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#29 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\InterestingMessage->handle()
#30 /var/www/firefly-iii/app/Http/Middleware/Binder.php(79): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#31 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\Binder->handle()
#32 /var/www/firefly-iii/app/Http/Middleware/Range.php(61): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#33 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\Range->handle()
#34 /var/www/firefly-iii/vendor/jc5/google2fa-laravel/src/Middleware.php(29): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#35 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): PragmaRX\\Google2FALaravel\\Middleware->handle()
#36 /var/www/firefly-iii/app/Http/Middleware/Authenticate.php(74): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#37 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\Authenticate->handle()
#38 /var/www/firefly-iii/vendor/laravel/passport/src/Http/Middleware/CreateFreshApiToken.php(50): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#39 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Laravel\\Passport\\Http\\Middleware\\CreateFreshApiToken->handle()
#40 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Session/Middleware/AuthenticateSession.php(58): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#41 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Session\\Middleware\\AuthenticateSession->handle()
#42 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/VerifyCsrfToken.php(77): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#43 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\VerifyCsrfToken->handle()
#44 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/View/Middleware/ShareErrorsFromSession.php(49): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#45 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\View\\Middleware\\ShareErrorsFromSession->handle()
#46 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Session/Middleware/StartSession.php(121): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#47 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Session/Middleware/StartSession.php(63): Illuminate\\Session\\Middleware\\StartSession->handleStatefulRequest()
#48 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Session\\Middleware\\StartSession->handle()
#49 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Cookie/Middleware/AddQueuedCookiesToResponse.php(37): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#50 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Cookie\\Middleware\\AddQueuedCookiesToResponse->handle()
#51 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Cookie/Middleware/EncryptCookies.php(67): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#52 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Cookie\\Middleware\\EncryptCookies->handle()
#53 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(103): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#54 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(693): Illuminate\\Pipeline\\Pipeline->then()
#55 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(668): Illuminate\\Routing\\Router->runRouteWithinStack()
#56 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(634): Illuminate\\Routing\\Router->runRoute()
#57 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Routing/Router.php(623): Illuminate\\Routing\\Router->dispatchToRoute()
#58 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(166): Illuminate\\Routing\\Router->dispatch()
#59 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(128): Illuminate\\Foundation\\Http\\Kernel->Illuminate\\Foundation\\Http\\{closure}()
#60 /var/www/firefly-iii/app/Http/Middleware/InstallationId.php(53): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#61 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\InstallationId->handle()
#62 /var/www/firefly-iii/vendor/fideloper/proxy/src/TrustProxies.php(57): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#63 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Fideloper\\Proxy\\TrustProxies->handle()
#64 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#65 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest->handle()
#66 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#67 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest->handle()
#68 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/ValidatePostSize.php(27): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#69 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\ValidatePostSize->handle()
#70 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/PreventRequestsDuringMaintenance.php(87): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#71 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): Illuminate\\Foundation\\Http\\Middleware\\PreventRequestsDuringMaintenance->handle()
#72 /var/www/firefly-iii/app/Http/Middleware/SecureHeaders.php(51): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#73 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(167): FireflyIII\\Http\\Middleware\\SecureHeaders->handle()
#74 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(103): Illuminate\\Pipeline\\Pipeline->Illuminate\\Pipeline\\{closure}()
#75 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(141): Illuminate\\Pipeline\\Pipeline->then()
#76 /var/www/firefly-iii/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(110): Illuminate\\Foundation\\Http\\Kernel->sendRequestThroughRouter()
#77 /var/www/firefly-iii/public/index.php(76): Illuminate\\Foundation\\Http\\Kernel->handle()
#78 {main}
"} 

[Dual-0]

I tried a new installation via compose too

Installing grumpydictator/firefly-iii (5.4.6)
  - Installing grumpydictator/firefly-iii (5.4.6): Loading from cache
Created project in /var/www/firefly-iii-updated
> @php -r "file_exists('.env') || copy('.env.example', '.env');"
> @php -r "if (!(getenv('DYNO'))===false){file_exists('.env') || copy('.deploy/heroku/.env.heroku', '.env');copy('.deploy/heroku/.locales', '.locales');}"
Loading composer repositories with package information
Installing dependencies from lock file
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for diglactic/laravel-breadcrumbs v6.0.2 -> satisfiable by diglactic/laravel-breadcrumbs[v6.0.2].
    - diglactic/laravel-breadcrumbs v6.0.2 requires php ^7.2 -> your PHP version (8.0.2) does not satisfy that requirement.
  Problem 2
    - Installation request for laravel/passport v10.0.1 -> satisfiable by laravel/passport[v10.0.1].
    - laravel/passport v10.0.1 requires php ^7.3 -> your PHP version (8.0.2) does not satisfy that requirement.
  Problem 3
    - Installation request for lcobucci/jwt 3.3.3 -> satisfiable by lcobucci/jwt[3.3.3].
    - lcobucci/jwt 3.3.3 requires php ^5.6 || ^7.0 -> your PHP version (8.0.2) does not satisfy that requirement.
  Problem 4
    - Installation request for league/csv 9.6.1 -> satisfiable by league/csv[9.6.1].
    - league/csv 9.6.1 requires php ^7.2.5 -> your PHP version (8.0.2) does not satisfy that requirement.
  Problem 5
    - Installation request for pragmarx/recovery v0.1.0 -> satisfiable by pragmarx/recovery[v0.1.0].
    - pragmarx/recovery v0.1.0 requires php ~7.0 -> your PHP version (8.0.2) does not satisfy that requirement.
  Problem 6
    - Installation request for tightenco/collect v8.0.4 -> satisfiable by tightenco/collect[v8.0.4].
    - tightenco/collect v8.0.4 requires php ^7.1.3 -> your PHP version (8.0.2) does not satisfy that requirement.
  Problem 7
    - tightenco/collect v8.0.4 requires php ^7.1.3 -> your PHP version (8.0.2) does not satisfy that requirement.
    - adldap2/adldap2 v10.3.1 requires tightenco/collect ~5.0|~6.0|~7.0|~8.0 -> satisfiable by tightenco/collect[v8.0.4].
    - Installation request for adldap2/adldap2 v10.3.1 -> satisfiable by adldap2/adldap2[v10.3.1].

[JC5]

Firefly III requires PHP 7.4.

[strangeglyph]

Are there plans to support PHP 8 at some point?

[JC5]

Absolutely. The new beta is compatible with both PHP 8.0 and 7.4. The docker image for the new beta runs PHP 8.0.1. If you try installing the "develop" version, you should have no problems with PHP 8.