Android app crashes with std::bad_cast on mavsdkServer.run("udp://:14550")

[josephm28]

Hi!

I'm using mavsdk:2.0.1 and mavsdk-server:2.0.0 in my Android app. I finally have everything compiling, but when I call mavsdkServer.run("udp://:14550"), I get an app crash with

libc++abi  E  terminating with uncaught exception of type std::bad_cast: std::bad_cast
libc  A  Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 16094 (mavsdk-event-qu), pid 15871

I've also been intermittently dealing with

java_vm_ext.cc:591] JNI DETECTED ERROR IN APPLICATION: field operation on NULL object: 0x0
java_vm_ext.cc:591]     in call to GetObjectField
java_vm_ext.cc:591]     from java.lang.String java.lang.Runtime.nativeLoad(java.lang.String, java.lang.ClassLoader, java.lang.Class)

but right now the first error is where I'm stuck.

I did see https://github.com/mavlink/MAVSDK-Java/issues/70 which looks like a similar error at the end of the thread, but no resolution there.

Do you have any suggestions?

[JonasVautherin]

Hmm... could you maybe try the latest version 2.1.0? https://central.sonatype.com/search?q=mavsdk

[josephm28]

Updated and I get the same two errors.

[josephm28]

I can get the sample android app working correctly, but the mavsdk version is pretty old. I'm trying to update that as well to 2.1.0 to narrow down issues.

[josephm28]

Here's a PR to update several pieces of the android-client, including the mavsdk 2.1.0 - https://github.com/mavlink/MAVSDK-Java/pull/170 seems to build and run okay (at least drone connection).

So now I'm wondering if there's some dependency issue in my app... but not sure what that would be.

[JonasVautherin]

@Sefibrah: Does 2.1.0 work for you? Just to have another data point

[josephm28]

I'm also occasionally seeing this error, again pointing to some weird dependency issue?

java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZNKSt6__ndk14__fs10filesystem4path10__filenameEv" referenced by "/data/app/~~8GsfdN9bL2Pf58nQvs0l8g==/com.dronedeploy.beta-tXNIZA4nw3M4Efvp3NFflw==/lib/arm64/libmavsdk_server.so"...
                                                                                                        at java.lang.Runtime.loadLibrary0(Runtime.java:1082)
                                                                                                        at java.lang.Runtime.loadLibrary0(Runtime.java:1003)
                                                                                                        at java.lang.System.loadLibrary(System.java:1661)
                                                                                                        at io.mavsdk.mavsdkserver.MavsdkServer.<clinit>(MavsdkServer.java:6)

[JonasVautherin]

Are you getting mavsdk from Maven or compiling it yourself?

[josephm28]

I'm using Maven.

We also use the DJI SDK in the same app and I think I've traced the issue to com.secneo.sdk. To set up that SDK, you configure (e.g. setup)

class MyApplication : Application() {
    override fun attachBaseContext(base: Context?) {
        super.attachBaseContext(base)
        // before installation, please don't use MSDK
        com.secneo.sdk.Helper.install(this)
    }
    ...
}

If you remove com.secneo.sdk.Helper.install(this) there are no issues with the JNI or the MAVSDK and I get a connection to the drone. Of course, that means that the DJI SDK doesn't work... So at least I know a bit more about what's causing it, but still not sure why it's causing the JNI crashes.

[Sefibrah]

@Sefibrah: Does 2.1.0 work for you? Just to have another data point

The update to 2.1.0 provided me a successful run, as well as a successful mission upload. However, when I tried again the same thing 2-3 months later, I encountered this issue #178, so I am not certain what is going on.