danke,
habe es geändert,
trotzdem sofort nach mymenu.init wieder der selbe runtime error mit der exeption

Exception (29):
epc1=0x40205d63 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

ctx: cont
sp: 3fff0280 end: 3fff0560 offset: 01a0

>>>stack>>>
3fff0420: feefeffe 00000028 3ffef250 402025a1
3fff0430: feefeffe feefeffe feefeffe feefeffe
3fff0440: feefeffe feefeffe feefeffe feefeffe
3fff0450: feefeffe feefeffe feefeffe feefeffe
Code:
tMenu mymenu(20,10);

void setup(void)
{

  Serial.begin(115200);
  delay(2000); // wait for Serial()
  Serial.println("Serial started");
  
  char test[15]="5 newline_";
  strcpy(mymenu.list[5], test);
  Serial.println(mymenu.list[5]);
   
  mymenu.list[5][0]='>';
  Serial.println(mymenu.list[5]);
  Serial.println();
  for(byte i=0; i<10; i++) {
     Serial.print("-");
     Serial.println(mymenu.list[i]);
  }

  // bis hierhin no problem


  mymenu.init();  // >>> runtime error, exeption
  // ...
}
Code:
 
class tMenu {
  
  protected:    
        int16_t  MENULEN, CAPTLEN; 
        char buf[20];                 
          
  
  public:      
     char    **list;     
     tMenu (int16_t menulen, int16_t captlen) // constructor
     {
        MENULEN = menulen;
        CAPTLEN = captlen;
       
        list = new char*[MENULEN];
        for(int i = 0; i < MENULEN; i++)
        {
          list[i] = new char[CAPTLEN];
        }        
     }      
     
     void init() {
        for(int i=0; i<MENULEN; i++) {
           sprintf(buf,"%d line %d", i);
           strcpy(list[i*MENULEN], buf);
        }
     }

 
};
(habe keinen debugger, nur die Arduino IDE)