How to set default action handler permanently? I've set defaults apps for many actions like sending email, opening PDFs, opening webpages etc. But, when I install or update an app which could handle that action, this default is cleared (even if default app is updated).

Nobody has problem with this because they can tick default checkbox on next action. My problem: I use Tasker to automate high amount of actions. And, due to this default removals (after automatic update), my tasks are stuck at Choose App pop-up. Tasks need to be completed in time. So, I face many real-world problems due to this.

What should I do to preserve defaults after automatic app update. Please, don't answer You can't or Turn off Automatic Update.
AFAIK, defaults on Android is not preserved if apps that use the intent are changed.

Workaround:

Use intent to launch the application or its activity screen.

intent is comparatively reliable though it may be changed when app is updated.

Take sending email as an example


Install Intent Intercept (Google Play)
Clear the defaults of email client
Choose "Intent Intercept" in Share menu when sending email
Copy intent details of your desired application activity
Open Tasker to "Create Task": Misc > Send Intent
Edit the parameters (Usually fill in the Action and Extra is enough)


Ref: http://tasker.dinglisch.net/userguide/en/intents.html

P.S. Some famous companies even provide you the intent details on their developer website, such as Evernote.