Crash when il2cpp 64bit Android app call a WWW request

Hello guys,
My app upgrades from 5.6 to 2017.4 due to 64bit requirement of google play.
It’s would crash when my app call a coroutine which would do a WWW request to my server.
Only in 64-bit version, Mono build and il2cpp 32-bit are fine.

Logcat shows

2019-11-27 16:31:42.569 26776-26891/com.myapp.app02 E/CRASH: #00 pc 0000000000491408 /data/app/com.myapp.app02-vtr3XhXUZWeFvLA3K8PK7g==/lib/arm64/libunity.so
2019-11-27 16:31:42.569 26776-26891/com.myapp.app02 E/CRASH: #01 pc 00000000004b84b8 /data/app/com.myapp.app02-vtr3XhXUZWeFvLA3K8PK7g==/lib/arm64/libunity.so
2019-11-27 16:31:42.569 26776-26891/com.myapp.app02 E/CRASH: #14 pc 0000000000268f34 /data/app/com.myapp.app02-vtr3XhXUZWeFvLA3K8PK7g==/lib/arm64/libunity.so
2019-11-27 16:31:42.575 26776-26807/com.myapp.app02 E/MessageQueue: IdleHandler threw exception
java.lang.Error: signal 6 (SIGABRT), code -6 (?), fault addr --------
Build fingerprint: ‘Nokia/TA-1003_00WW/D1C:8.1.0/OPR1.170623.026/00WW_5_620:user/release-keys’
Revision: ‘0’
pid: 26776, tid: 26891, name: Thread-31 >>> com.myapp.app02 <<<
x0 0000000000000000 x1 000000000000690b x2 0000000000000006 x3 0000000000000008
x4 0000000000000000 x5 0000000000000000 x6 0000000000000000 x7 7f7f7f7f7f7f7f7f
x8 0000000000000083 x9 0000000010000000 x10 0000007e81d0a760 x11 0000000000000001
x12 0000007e81d0a258 x13 ffffffffffffffff x14 ff00000000000000 x15 ffffffffffffffff
x16 0000005ed1eaefa8 x17 0000007f28637c1c x18 0000000000000000 x19 0000000000006898
x20 000000000000690b x21 0000000000000083 x22 0000000000000002 x23 0000007e81d0b588
x24 0000007e81d0a7f9 x25 000000000000120b x26 0000007e75c9a000 x27 000000000000120a
x28 0000000000000043 x29 0000007e81d0a7a0 x30 0000007f285ecb6c
sp 0000007e81d0a760 pc 0000007f285ecb94 pstate 0000000060000000

at libunity.00491408(Native Method)
at libunity.004b84b8(Native Method)
at [vdso].__kernel_rt_sigreturn(__kernel_rt_sigreturn:0)
at libc.abort(abort:120)
at libart.art::Runtime::preZygoteFork()(Runtime:0)
at libart.android::base::LogMessage::~LogMessage()(base:1008)
at libart.art::JavaVMExt::JniAbort(char const*, char const*)(JavaVMExt:1716)
at libart.art::JavaVMExt::JniAbortF(char const*, char const*, …)(JavaVMExt:184)
at libart.art::thread::smile:ecodeJObject(_jobject*) const(art:468)
at libart.000e83dc(Native Method)
at libart.000e8cb8(Native Method)
at libart.000e7040(Native Method)
at libart.000ec43c(Native Method)
at libart.000ecf6c(Native Method)
at libunity.00268f34(Native Method)
at libil2cpp.014f9144(Native Method)
at libil2cpp.014f032c(Native Method)
at libil2cpp.014f0094(Native Method)
at libil2cpp.0148ba50(Native Method)
at libil2cpp.014f1864(Native Method)
at libil2cpp.01912ca4(Native Method)
at libil2cpp.01913544(Native Method)
at libil2cpp.01913458(Native Method)
at libil2cpp.01862b70(Native Method)
at libil2cpp.007c8a04(Native Method)
at libil2cpp.0189846c(Native Method)
at libil2cpp.01898cc0(Native Method)
at libil2cpp.01898c5c(Native Method)
at libil2cpp.018bb834(Native Method)
at libil2cpp.018d2a18(Native Method)
at libil2cpp.018bb724(Native Method)
at libil2cpp.018bf718(Native Method)

I tried to de-symbolize the top address 491408, and it shows SkinnedMeshRendererManager::TryPrepareOptimizedRenderer(int).
I have no idea about it.

PLEASE HELP ME!

What does that WWW request download? Can you show the code?