When trying to connect an emulator with version 21, occasionally getting the error

11:58:24 error: device offline
11:58:24 $ /data/kira/Utils/android-sdk-linux//platform-tools/adb connect localhost:44453
11:58:37 $ /data/kira/Utils/android-sdk-linux//platform-tools/adb -s localhost:44453 shell getprop dev.bootcomplete

I'm trying with an android plugin version v2.10 as well as the latest one.
The problem does not occur with version 17, but my minimu, version is above that.
I saw many comments on this issue, but none explained if the issue is resolved