I moved your comment to a new discussion topic as the 6 year old topic you posted to is not relevant.
There is no substitute plugin for Flash Player. The solution is for content creators to migrate their content to a different technology.
Adobe announced Flash Player's end-of-life in July 2017 giving content creators, programmers, developers, IT experts, etc over 3 years remove Flash Player dependencies from their products. All modern browsers provide the capabilities necessary to do this in JavaScript. This is an investment and prioritization choice, not a technical limitation.
For reference:
Major browser vendors are deprecating Flash Player support. Details specific to each vendor:
- Apple Safari - removed Flash Player support in Safari 14, released Sept 16, 2020
- Google Chrome - removed Flash Player support in Chrome 88, released Jan 19, 2021
- Firefox - removed Flash Player support in Firefox 85, released on Jan 26, 2021.
- Firefox ESR 78 will support Flash Player for the time being, assuming the Flash Player NPAPI plugin is already installed as it’s no longer available for download.
- Microsoft Edge - removed Flash Player support in Edge 88, released Jan 15, 2021
- Microsoft Internet Explorer and legacy Edge
For users attempting to view Flash content, contact the content creators and inquire about their plans to migrate their content to some other technology.