I'am unable to install the official MyJDownloader Chrome addon, due to the forced switch to manifestV3, what can I do about it?

The background:

Google decided to drop support for "manifestV2" in favor of "manifestV3" which makes our addon [officially] incompatible with the current Chrome versions.
This means that a lof of older addons won't be usable at all anymore for several reasons which include:

• their developers being inactive
• the addons using features which are not available for manifestV3 addons anymore

In our case, our MyJD addon is using features which are not possible to use anymore via manifestV3.
Do a websearch on "Chrome manifestV3" if you are interested to find out more about this topic.

Possible solutions

1. Easiest solution: switch to another browser that continues to support manifestV2 for example
   - Firefox
   - Brave
   - Vivaldi
   - Opera
   - Ungoogled Chromium: https://github.com/ungoogled-software/ungoogled-chromium
   - Edge
2. or: get a portable version of a manifestV2 supported browser and use that only for the MyJD addon.
   Important: If you decide to use another browser and if that browser is not your systems' default browser you need to configure JD to use a non-default browser for captcha solving.
3. or: do not use a browser at all for browser captchas, see browser captcha article, section "I do not want to use a browser for captcha solving".

If you wish to keep using Chrome, continue reading!

How to prolong Chrome manifestV2 support

New way for Chrome version 140 and higher (all OS)

Start Chrome with these parameters: --disable-features=ExtensionManifestV2Unsupported,ExtensionManifestV2Disabled

Under Windows, this means, create a shortcut with: chrome.exe --disable-features=ExtensionManifestV2Unsupported,ExtensionManifestV2Disabled

Credits

New way for Chrome version 139 and higher (all OS)

1. Open a new tab -> Type in chrome://flags/#temporary-unexpire-flags-m137 in the address bar -> Set to Enabled
2. Restart Chrome
3. Now using the same method, apply the following settings:
   chrome://flags/#extension-manifest-v2-deprecation-warning Disabled
   chrome://flags/#extension-manifest-v2-deprecation-disabled Disabled
   chrome://flags/#extension-manifest-v2-deprecation-unsupported Disabled
   chrome://flags/#allow-legacy-mv2-extensions Enabled
4. Restart Chrome and navigate to the Chrome MyJD addon in the Chrome Webstore which is linked here: my.jdownloader.org/apps/
5. Install the addon. If it remains not-installable, use another browser instead or try these instructions again from the beginning.

Credits

Older ways (probably not working anymore or only for older Chrome versions)

Windows users
Tweak your registry to allow the prolonged usage of manifestV2 addons in Chrome, see: https://www.regfiles.net/registry/extend-extension-manifest-v2-availability-registry
-> Go to the linked website -> Scroll down and click on the blue "Download" button -> Double click the downloaded .reg file to apply it to your Windows registry

Windows users (without registry change) and all others (Mac/Linux)

Open a new Tab -> Enter the following in the address bar and press enter ->  chrome://flags/#allow-legacy-mv2-extensions -> Set this to "Enabled"
See also: https://stackoverflow.com/questions/79283218/running-unpacked-chrome-extensions-through-the-manifest-v2-deprecation

Another useful guide about how to prolong manifestV2 usage, with specific tutorials for other OS like Linux and Mac:

https://gist.github.com/velzie/053ffedeaecea1a801a2769ab86ab376

And yet another one:

https://www.reddit.com/r/uBlockOrigin/comments/1mtowwf/end_of_support_for_ubo_on_chrome_chromium/