The error you're encountering is due to Android's security restrictions: ADD_TRUSTED_DISPLAY is a system-level permission that is not directly grantable to third-party apps (like Termux) via standard Android permission mechanisms. This permission is typically reserved for system apps or services with elevated privileges.

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Why is this happening?

• ADD_TRUSTED_DISPLAY is a system-only permission, meaning only apps signed with the platform key (i.e., built into the Android system) can use it.
• The Android framework enforces this restriction to prevent unauthorized apps from creating trusted virtual displays, which could be used for sensitive operations (e.g., screen recording, input injection).

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Possible Workarounds

1. Root Access (Not Recommended for Security Reasons)

• If your device is rooted, you could use tools like su to run Termux as root and bypass the permission check.
• Warning: This is not secure and can expose your device to malware.

2. Modify Android Framework (Advanced)

• If you have the Android source code, you could modify the DisplayManagerService to allow your app to use the permission.
• This requires compiling your own Android ROM, which is complex and not practical for most users.

3. Use ADB Shell (If Possible)

• If you have ADB access, you could try running the command directly from a shell with root privileges:

  bash
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  adb shell su -c "app_process -Djava.class.path=/path/to/your/app / com.termux.api.TermuxApiReceiver createVirtualDisplay ..."

• This is still not guaranteed to work, as the permission check is enforced by the framework.

4. Request the Permission in Your App Manifest (Not Sufficient)

• Even if you declare the permission in your AndroidManifest.xml, Android will still enforce the system-only restriction:

  xml
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  <uses-permission android:name="android.permission.ADD_TRUSTED_DISPLAY" />

• This will not grant the permission; it only declares your intent to use it.

5. Use a System App

• If you can build your app as a system app (e.g., by flashing a custom ROM or using a rooted device), you can sign it with the platform key and use the permission.

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Conclusion

There is no standard way to grant the ADD_TRUSTED_DISPLAY permission to a third-party app like Termux without rooting or modifying the Android framework. The restriction is intentional for security reasons.

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If you are developing this for a specific use case (e.g., screen mirroring, accessibility), consider alternative approaches, such as using non-trusted virtual displays or leveraging other APIs (e.g., MediaProjection for screen capture).

Would you like help exploring alternative solutions for your specific use case?