rxdart と flutter_plugin_pdf_viewer の 2 つのパッケージをインストールしています。
rxdart: ^0.23.1
flutter_plugin_pdf_viewer: ^1.0.7
ただし、flutter_plugin_pdf_viewer >=1.0.4 は禁止されています。
これはエラーメッセージです：
Because flutter_plugin_pdf_viewer >=1.0.4 depends on rxdart ^0.21.0 and flutterattendancesystem depends on rxdart ^0.23.1, flutter_plugin_pdf_viewer >=1.0.4 is forbidden.
So, because flutterattendancesystem depends on flutter_plugin_pdf_viewer ^1.0.7, version solving failed.
pub upgrade failed (1; So, because flutterattendancesystem dep
ends on flutter_plugin_pdf_viewer ^1.0.7, version solving failed.)