ESP32 -- Stack smashing protect failure!

Hello friends.

Unfortunly i am struggling with the following problem. I am using an ESP32 and a Nextion display.
For the Nextion displayi am using the Nextion.h libary.

The problem is relativly simple. I created a dualstatebutton in my Nextion.
Fruther i just want to read the curent state of the button, for this case i am using the following libaryfunction:

bool NexDSButton::getValueDS(String x,uint32_t *number)
    String cmd = String("get ");
    cmd += x;
    cmd += ".";
    cmd += getObjName();
    cmd += ".val";
    return recvRetNumber(number);

I will not post the whole code here, since it is very long, but when i call the function in my code like the following,

void sondenwahlpHPopCallback(void *ptr)
  uint32_t _sondenstatepH;

SondenwahlpH is defined: NexDSButton sondenwahlpH = NexDSButton(26,6,"bt0");

i get is the following:

Stack smashing protect failure!

abort() was called at PC 0x400def2c on core 1

Backtrace: 0x4008c714:0x3ffb1db0 0x4008c945:0x3ffb1dd0 0x400def2c:0x3ffb1df0 0x400d65db:0x3ffb1e10 0x400d4065:0x3ffb1e40 0x4011a935:0x3ffb1e80 0x400d71ca:0x3ffb1ea0 0x400d69be:0x3ffb1ec0 0x400d5c63:0x3ffb1ef0 0x400dc09d:0x3ffb1fb0 0x40088e19:0x3ffb1fd0

ets Jun 8 2016 00:22:57

This error occurs not everytime. I havnt found any pattern. Sometimes it works sometimes it shows the error. Theses problems are always the hardest, that show no patterns

I have done some research, but now found a solution. Again, i did not post the whole code by intention because i think its easier to cut it short.

Has anyone hints where the problem could lay?

Anyone has an idea?

best regards