I always have to scan my implant twice to generate my OTP codes, because the first scan keeps giving this error:
It used to just pull up the codes on first scan. any help in fixing this would be appreciated! 
Iâm on version 3.4.9
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Iâm on the same version but donât have this problem.
Are you set up to go straight to OTP on scan?
What apps do you have on your Apex?
yes i have ânavigate to OTP screen on initial scanâ enabled
installed apps are: hmac-sha1, otp authenticator, free memory, fido security
Has the phone or apps changed?
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sadly no, same phone since i put the implant in. i tried uninstalling and re-installing the app but i still get that error. i can still get my codes thankfully, it just requires two scans so itâs a bit of an annoyance
The only thing I can think of is a coupling problem. Initial scan does a lot.. itâs probing all the apps itâs selecting all the AIDs, and then finally pulling all the OTPs. If thereâs a problem with the coupling at any point, it will show this error.
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Thereâs another possibility though. Has your phone had an update? My nothing phone 2 was working awesome with NFC tags, then I updated it and it continued to be absolute shit at reading anything until I had to fucking contact the goddamn engineer in Taiwan who built the NFC stack for the phone to tell me fucked it up. He gave me a preview patch which fixed it, then they pushed it in there next update.
Updates can always break shit.
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i have updates disabled on my phone and im not sure if its coupling issue because it worked fine in the past. unclear what changed 
is there a log file somewhere hidden in the app that could give me more details on the error?
@hoker may have put a secret log view in but adb logcat should output some useful information if you have developer tools on and want to debug it.
Clearly something has changed.. and if the phone hasnât changed, you havenât installed any other NFC apps, you havenât changed NFC settings (google pay?), the app hasnât changed, and settings on the app havenât changed, then that leaves;
- your behavior
- your implant
Hopefully this is not an indication the implant is slowly losing performance (failing? infiltration?)
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- Are other applets working properly? As in, is the correct state loading for things other than OTP?
- Is your OTP applet password protected
- Can you try disabling the âNavigate to OTPâ settings option and try scanning from launch again
- If you go to settings and tap the version number at the bottom and then scroll to the top of the screen, you should see an âExport Logcatâ option. It will write a logcat dump to your documents folder (I think thatâs where I put it). Go ahead and DM me the logcat if youâre cool with it.
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After doing this, scaning implant brings up the list of features, and then when i click authenticator, it shows the same error message. then re-scanning brings up my otp codes
yeah, since the day i had it put in. have the password cached into the app
yeah all the applets work, its just the OTP applet that requires a second scan to actually get at the codes whereas before it would just bring them up on the first scan with no error.
DMâd you
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What phone are you using? Would you mind doing something really annoying for me?
It sounds like a potential coupling issue. Like @amal said, the initial scan in Apex Manager is doing a LOT. Itâs manually sniffing out what applets are installed, and then performing actions (like OTP code generation, 2 passes btw) for each applet that is installed. I currently have the app wired where if an applet action doesnât 100% succeed, it wonât necessarily count as a bad scan, but the applet that failed to run itâs actions will simply require a rescan.
OTP is currently the heaviest applet in terms of raw APDUs running under the hood on initial scan.
Anyways, back to the annoying thing. Will you as carefully as possible, position your phone as perfectly on your implant as possible while on the Apex Manager initial screen (with navigate to OTP off). Get like 10 scans from the initial screen and let me know if any of them result in the OTP creds showing without you first having to rescan.
I just want to know if thereâs ever a time when they generate properly from initial scan. Iâll dig through your logcat now in the meantime:)
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Hey, one more thing, does a version number show on the right side of the OTP applet card on the Apex Manager main screen post-initial scan?
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No it just says authenticator and then a â>â on the right side of that
I tried this and none of the scans from the initial screen worked (but then scanning a second time from the error message screen works fine), do you want the logcat from these attempts as well?
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Nah, youâre good. Thanks though. Your first logcat actually pointed me to what I believe is the smoking gun. You have an old version of the OTP applet. It has a different AID and I believe whatâs happening is the code that fires from the initial scan is using the new AID exclusively, while on the OTP screen itself, I have a fallback option to the old AID if the new one doesnât work. If itâs alright with you, Iâll try and fix this on my end and then send you a test APK to have you test and confirm itâs been resolved. Unfortunately I donât have any P71s with the old OTP applet on it so I canât verify myself easily. Is that cool with you? I can work on a fix now.
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Thanks for reporting this issue @pac ! I never wouldâve found this otherwise
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Little update, I had to make a change to my underlying NFC library to add the old AID in. Itâs currently running a new build now. Once thatâs done, Iâll pull it down and cut a new test build of Apex Manager and send you an APK @pac .
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happy to test the apk for ya i can also update my otp applet
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Eh, Itâs a pain to update the applet cause youâd lose all your OTP credentials. If you donât mind, give this a test first at least:) Building the APK now with the potential fix. Fingerâs crossed!
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Iâll DM it to ya
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