Status update:
As it happens, I took the opportunity of having the phone on the dev channel to re-test an application that typically froze the GUI (the app called "Steps" -- I already opened a bug report on that specific issue). Turns out the behaviour was the same on v763, so I wanted to force a power cycle by rebooting the phone on the recovery image (Power + Vol+).

But instead of the recovery menu, I was greeted by the spiralling animation: the phone was clearly installing something. When it finished rebooting, I was back on OTA-20, and both SIMs were still active!

Following @DPITTI suggestion, I also removed v763 from the upgrade history.

I'll now mark this post as "resolved". Many thanks to all those who contributed.

Problem has been resolved -- phone is now running UT OTA-19 stable.

Details about the fix in the device-specific post (see URL in previous post). I'll now mark this one as resolved as well.

Many thanks to all those who helped.

@alter Thinking back about the whole sequence, I'm a bit concerned that my first failed attempt at flashing UT (before adapting the udev rules) may have left the phone in an "unexpected" state, which in turn caused the 2nd flashing attempt to fail with these ominous error messages.

It is perhaps best at this point that use TWRP again to put Android9 back on the phone (in both slots), make sure the phone is bootable again, and retry the whole 'ubports-installer' process again.

@dpitti The device initially came with Android 8.1, but I flashed it with v9 as recommended before proceeding with the UT installation.

Just upgraded to OTA-20: the upgrade process itself went flawlessly, but the SIM card in slot #1 is no longer detected!

• during startup, I'm prompted for only one PIN code (the prompt no longer identifies the SIM, but the code only matches SIM #2)
• in "settings | mobile", only one SIM and matching operator is listed (the one for SIM #2)
• same thing in the top-of-screen quick access bar
• "setting | about" reports OTA-20

Is there any information I could collect on the phone to help troubleshoot this?

Many thanks to all those who commented.

I'll apply OTA-20 in the coming days and report back.

Hello,

In a recent post dated Nov. 20, @magnargj mentioned that applying OTA-20 on his Mi A2 caused a problem with the 1st SIM slot, which he resolved by moving the card to the 2nd slot.

I'm currently using both slots (private + professional SIMs), which works fine on OTA-19, and I would like to know what to expect before deciding to apply OTA-20.

• Can anyone confirm or deny the issue with dual-SIM support on the Mi A2 under OTA-20?
• If confirmed, is there a workaround (that preserves dual-SIM functionalities)?
• If confirmed, is this issue tracked somewhere?

TIA

OK -- many thanks to "Shou" and "Kisekinopureya" who helped on Telegram.

First suggestion was to run "./fastboot flashing unlock_critical" (after having flashed stock Android 9, but before starting the UPI). That turned out not changing anything.

The second suggestion was to wipe user data and cache using "./fastboot -w" (once again, before starting the UPI), and this did the trick

My phone now happily runs UT!

@magnargj Yes, that's correct. Either 'volume down' + 'power' or "adb reboot bootloader". Same result in both cases.

Following the suggestion of a nice troubleshooting page about the "unknown command" issue, I also replaced the 'android-tools' RPM I was using (I'm on OpenSUSE Leap 15.2) by the official Google SDK ZIP file.

After doing this, the "fastboot boot twrp.img" command issued a different message ("sending twrp.img...") and just hung.

I'm also confused about this Xiaomi-specific unlock process. I found their FAQ (here: https://c.mi.com/thread-2262302-1-0.html) and in there they say: "For Android One users, please check out the unlocking tutorial in your device subforum. You don't have to go through the procedures mentioned here." They also say (further down): "How to check whether the bootloader is locked/unlocked? [...] An "Unlocked" word will be shown when booting." which is already the case on my phone.

@phandersson
Further experimental results. I just watched a tutorial video on how to root the phone (just in case), and it starts with early steps that are very similar to the ones I followed, so I tried those as well:

• enable dev mode + USB debug (already done, obviously)
• connect phone to PC
• type "adb devices" => device is listed:

$ adb devices -l
List of devices attached
dbXXXX                 device usb:1-1 product:jasmine model:Mi_A2 device:jasmine_sprout transport_id:2

• type "adb reboot bootloader" to reach fastboot: the phone does reboot and reaches the fastboot splash screen
• use fastboot to boot on TWRP image -- this time, the message was different (although it still doesn't work):

$ fastboot boot ./twrp-3.5.2_9-0-jasmine_sprout.img
Downloading 'boot.img'
FAILED (data write failure (Cannot send after transport endpoint shutdown))
Finished. Total time: 0.850s

And indeed, the fastboot environment appears to have crashed: the fastboot splash screen is gone, and the phone displays a short text message: "press any key to shutdown" (pressing power then reboots the phone).

As the message could hint at a data transmission problem, I tried the same procedure with the other USB-C cable, and this time the output for the last step was:

$ fastboot boot ./twrp-3.5.2_9-0-jasmine_sprout.img
Downloading 'boot.img'
FAILED (remote: unknown command)
Finished. Total time: 0.012s

So, similar to the behaviour described in my initial post above. But I'm a bit concerned by this lack of repeatability...

After retesting yesterday and today, issue no longer manifest itself (don't know why). And that also covers waking up the phone by touching the fingerprint sensor at the back.

In any case, thread can be marked as resolved (my apologies for the noise).

Small clarification: if the USB cable is plugged after unlocking the phone (I'm talking about the UT-level PIN, not the SIM PIN), then charging takes place as expected.

@lakotaubp Many thanks for the pointer. Problem reported as https://github.com/ubports/ubuntu-touch/issues/2076.

I applied OTA-24 yesterday. Since then, the phone no longer charges when I plug it into the PC while booted to UT. When I do, the battery icon turns green and the lightning symbol appears for about one second, then it disappears and the battery icon turn white again. If I let it plugged in for hours, the battery charge doesn't increase.

Turning the phone off and plugging it to a regular USB charger still works, thankfully.

Another side effect of the latest update is that touching the fingerprint sensor at the back no longer wakes the phone up (not a big deal as far as I'm concerned, but a regression nonetheless).

Status update:
As it happens, I took the opportunity of having the phone on the dev channel to re-test an application that typically froze the GUI (the app called "Steps" -- I already opened a bug report on that specific issue). Turns out the behaviour was the same on v763, so I wanted to force a power cycle by rebooting the phone on the recovery image (Power + Vol+).

But instead of the recovery menu, I was greeted by the spiralling animation: the phone was clearly installing something. When it finished rebooting, I was back on OTA-20, and both SIMs were still active!

Following @DPITTI suggestion, I also removed v763 from the upgrade history.

I'll now mark this post as "resolved". Many thanks to all those who contributed.

@lakotaubp said in Dual-SIM + OTA-20 on Mi A2:

@phandersson So you are back on stable with 2 simsworking?

The 2 SIMs are working again, yes, but I'm still on "devel" (v763), and apparently unable to get back to "stable". I can select the channel, but nothing gets downloaded.

Might just be an overlap of updates between being on dev and going back to stable. Should be safe enough to ignore it and carry on the next stable update should remove it.

You mean, switch to "stable" even if nothing happens, and wait for OTA-21 to be released? I can try. Although representing heavier work, I guess I could also re-install the phone from scratch on OTA-20 using UTI.

By the way, the problem of dual-SIM support in OTA-20 is a known bug (just found out about it):

https://github.com/ubports/ubuntu-touch/issues/1879

...and a manual fix is provided in the post by "laguna66".

@lakotaubp Same behaviour after power cycle.

What's strange is that after switching back to the stable channel, the main "Settings" screen shows 1 update available (see screenshot below):

But when tapping on that line, and after "checking for updates", it still returns "Software is up to date".

Well, I can select the stable channel again, but nothing happens: the updater doesn't detect anything to download (even after closing and restarting the "Settings" app).

@lakotaubp Following your suggestion, I just switched to "dev" channel and installed the image (ver. 763).

I'm happy to report that this restored access to both SIM slots -- see screenshot below:

I'll now switch back to the stable channel and report again.

@c4pp4 I tried to follow the procedure you suggested, but without success so far.

Right after switching to the "dev" channel, the phone downloaded a 500MB installation image (which I didn't actually install, obviously), but once I returned to the stable channel, nothing more happened. It still shows the dev image ready for install, but nothing new for the already installed system (see attached screenshot).

Likewise in "About | Check for updates" -- it checks, then shows the exact same thing.