Describes the cause and action for error messages.
Error Message(English)：
fatalthrowableerror class 'excel' not found
Class 'Maatwebsite\\Excel\\ExcelServiceProvider' not found ...
https://stackoverflow.com/questions/54083863/class-maatwebsite-excel-excelserviceprovider-not-found-・・・
laravel 5.7 "Class 'Maatwebsite\Excel\ExcelServiceProvider' not ...
https://stackoverflow.com/questions/54031664/laravel-5-7-class-maatwebsite-excel-excelserviceprovide・・・
"Class 'App\Http\Controllers\InvoicesExport' not found" in ...
https://stackoverflow.com/questions/50246497/class-app-http-controllers-invoicesexport-not-found-in-・・・
Class 'App\Http\Controllers\Excel' not found in Laravel
https://stackoverflow.com/questions/30155145/class-app-http-controllers-excel-not-found-in-laravel
Class 'App\Http\Controllers\Excel' not found in Laravel - Stack Overflow
https://stackoverflow.com/questions/30155145/class-app-http-controllers-excel-not-found-in-laravel/3・・・
Followed instructions but still Class 'Excel' not found ・ Issue #510 ...
https://github.com/Maatwebsite/Laravel-Excel/issues/510
Class 'Maatwebsite\Excel\Excel' not found ・ Issue #1783 ・ Maatwebsite ...
https://github.com/Maatwebsite/Laravel-Excel/issues/1783
Laravel 5.2 で Excel出力 - Qiita
https://qiita.com/UedaTakeyuki/items/0255ed7c9ccdcd83263b
laravel excel installation issue - Laracasts
https://laracasts.com/discuss/channels/general-discussion/laravel-excel-installation-issue