App Keu is invalid

Hey there. i have published application with Vuforia.  Some user have very strange issue.  they are getting error message  App Key is invalid, and after few second(not always) app crashes.  is there any idea what is happening?  here is the crash log; signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 0x7b1c8a3be0     x0  0000007b1c8a3be0  x1  0000007b1c8a3be0  x2  0000007ca777d678  x3  0000007b59ea3823     x4  0000000000000be0  x5  0032663500000000  x6  0000000000000000  x7  0000008080808080     x8  0000007ca777d5f8  x9  000000000000007b  x10 0000007bb3aad2b4  x11 000000000000004f     x12 0101010101010101  x13 0032006600350031  x14 0000000000000003  x15 0000000000000020     x16 0000007bb389f2f0  x17 0000007db6e16080  x18 0000000000000000  x19 0000007ca777d560     x20 0000007b1c8a3be0  x21 0000007ca777f020  x22 0000007ca9cd21e0  x23 0000000000000002     x24 0000007ca777f020  x25 0000007c215d3ee0  x26 0000007ca777f020  x27 0000000000000a76     x28 0000007c400a3a68  x29 0000007ca777d6a0     sp  0000007ca777d530  lr  0000007bb22a3f10  pc  0000007db6e1608c

backtrace:       #00 pc 000000000006c08c  /apex/com.android.runtime/lib64/bionic/libc.so (strlen+12) (BuildId: 172150a75e0e5909a0b7b1af9540b91e)       #01 pc 000000000012ff0c  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libVuforia.so (BuildId: 2c42305a2e35fed2e309caf0a00ed92a35618eb5)       #02 pc 00000000001515bc  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libVuforia.so (BuildId: 2c42305a2e35fed2e309caf0a00ed92a35618eb5)       #03 pc 000000000015128c  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libVuforia.so (BuildId: 2c42305a2e35fed2e309caf0a00ed92a35618eb5)       #04 pc 0000000000151a9c  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libVuforia.so (Vuforia::setHint(unsigned int, int)+384) (BuildId: 2c42305a2e35fed2e309caf0a00ed92a35618eb5)       #05 pc 000000000001ea40  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libVuforiaWrapper.so (setApplicationEnvironment+56) (BuildId: a919ee47ce8dadc2408668d89cacdb96358b8ec1)       #06 pc 0000000000a8f694  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libil2cpp.so (BuildId: 02f055ed769283aebe5133654098dea473074411)       #07 pc 0000000000a92620  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libil2cpp.so (BuildId: 02f055ed769283aebe5133654098dea473074411)       #08 pc 00000000009302a4  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libil2cpp.so (BuildId: 02f055ed769283aebe5133654098dea473074411)       #09 pc 0000000000e10a88  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libil2cpp.so (BuildId: 02f055ed769283aebe5133654098dea473074411)       #10 pc 0000000000641f14  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libil2cpp.so (BuildId: 02f055ed769283aebe5133654098dea473074411)       #11 pc 0000000000780070  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libil2cpp.so (BuildId: 02f055ed769283aebe5133654098dea473074411)       #12 pc 000000000060bbcc  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #13 pc 0000000000619458  /data/app/com.arloo***pa.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #14 pc 0000000000622adc  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #15 pc 00000000006226bc  /data/app/com.***.**-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #16 pc 00000000006246b4  /data/app/com.**.**-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #17 pc 0000000000624b84  /data/app/com.**.****-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #18 pc 00000000006253ac  /data/app/com.**.**-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #19 pc 0000000000625bb0  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #20 pc 00000000004781d4  /data/app/com.**.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #21 pc 0000000000533c44  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #22 pc 0000000000533c78  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #23 pc 0000000000533ebc  /data/app/com.**.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #24 pc 0000000000689bec  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #25 pc 000000000069f4bc  /data/app/com.***.***-J4DURk434YNgagNKoJAzmw==/lib/arm64/libunity.so (BuildId: 3e69862be560f6de556fe083a94e71c33b68490a)       #26 pc 000000000005f07c  /data/app/com.***.**-J4DURk434YNgagNKoJAzmw==/oat/arm64/base.odex

at libc.strlen(strlen:12) at libVuforia.0x12ff0c(Native Method) at libVuforia.0x1515bc(Native Method) at libVuforia.0x15128c(Native Method) at libVuforia.Vuforia::setHint(unsigned int, int)(setHint:384) at libVuforiaWrapper.setApplicationEnvironment(setApplicationEnvironment:56) at libil2cpp.0xa8f694(Native Method) at libil2cpp.0xa92620(Native Method) at libil2cpp.0x9302a4(Native Method) at libil2cpp.0xe10a88(Native Method) at libil2cpp.0x641f14(Native Method) at libil2cpp.0x780070(Native Method) at libunity.0x60bbcc(Native Method) at libunity.0x619458(Native Method) at libunity.0x622adc(Native Method) at libunity.0x6226bc(Native Method) at libunity.0x6246b4(Native Method) at libunity.0x624b84(Native Method) at libunity.0x6253ac(Native Method) at libunity.0x625bb0(Native Method) at libunity.0x4781d4(Native Method) at libunity.0x533c44(Native Method) at libunity.0x533c78(Native Method) at libunity.0x533ebc(Native Method) at libunity.0x689bec(Native Method) at libunity.0x69f4bc(Native Method) at base.0x5f07c(Native Method)