I found a very annoying "bug" on the Nokia 6212 NFC and Nokia 6131 NFC.
I was building an obfuscated MIDlet when all of a sudden it started crashing on the NFC phones mentioned above. The 6212 and 6131 were crashing before starting the application, so it got me thinking that it might be a verification issue.The crash was followed by a warm reset of the phone and after 4 consecutive crashes by a cold reset of the phone.
I tested in the emulator and everything was fine. I tested on other phones and again, no problem.
I tried to exclude classes from the build that I thought were not verified correctly but I had to give up because of the huge number of classes ~approx 500.
I removed the code requiring permissions and signed the MIDlet. Still no luck.
I started looking at the SVN, since I knew the application was previously working. I noticed something. The icon.png of the MIDlet used to be 24 bits of color and now it was 32 bits. Somebody has changed the icon. I knew the Nokia 6131 NFC and 6212 NFC don't support such a high image depth so I rolled back the icon to 24 bits. TADAAA, I was now able to successfully obfuscate and run the application on the NFC phones.
This has been a really annoying and difficult to spot bug.