Code only works once, until reset

[gigawatts]

This sketch only seems to work once. Let me explain.

I flash your code, unmodified, to an ESP32 (in this case, its a CAN32 board, using a ESP32-WROOM-32U module, using the SparkFun ESP32 Thing board profile in the Arduino IDE), it starts fine. I connect to it from a phone, and I can send/receive messages without any issues. I can disconnect from the ESP AP, reconnect, and it still works. So far so good.

However, If I restart the ESP32 (reset button or power cycle), as soon as my phone tries to reconnect to it, I get the following error over and over in the serial term:

Rebooting...
ets Jun  8 2016 00:22:57

rst:0xc (SW_CPU_RESET),boot:0x17 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:1044
load:0x40078000,len:10044
load:0x40080400,len:5900
entry 0x400806ac
Guru Meditation Error: Core  0 panic'ed (InstrFetchProhibited). Exception was unhandled.
Core 0 register dump:
PC      : 0x00000000  PS      : 0x00060e30  A0      : 0x80107389  A1      : 0x3ffcc720  
A2      : 0x3ffd6ff8  A3      : 0x3ffd77e8  A4      : 0x3ffd6df8  A5      : 0x3ffd6cf8  
A6      : 0x0201a8c0  A7      : 0x0c01a8c0  A8      : 0x8010722c  A9      : 0x3ffcc6e0  
A10     : 0x3ffd7008  A11     : 0x3ffd77e8  A12     : 0x3ffcc72c  A13     : 0x00000044  
A14     : 0x00000001  A15     : 0x00000006  SAR     : 0x00000010  EXCCAUSE: 0x00000014  
EXCVADDR: 0x00000000  LBEG    : 0x4000c349  LEND    : 0x4000c36b  LCOUNT  : 0x00000000  

ELF file SHA256: 0000000000000000000000000000000000000000000000000000000000000000

Backtrace: 0x00000000:0x3ffcc720 0x40107386:0x3ffcc760 0x40115261:0x3ffcc780 0x4011a1e9:0x3ffcc7c0 0x4011f4a2:0x3ffcc7e0 0x40107d8f:0x3ffcc800 0x4008e0b9:0x3ffcc830

Rebooting...
ets Jun  8 2016 00:22:57

rst:0xc (SW_CPU_RESET),boot:0x17 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:1044
load:0x40078000,len:10044
load:0x40080400,len:5900
entry 0x400806ac
Guru Meditation Error: Core  0 panic'ed (InstrFetchProhibited). Exception was unhandled.
Core 0 register dump:
PC      : 0x00000000  PS      : 0x00060e30  A0      : 0x80107389  A1      : 0x3ffcc720  
A2      : 0x3ffd79e0  A3      : 0x3ffd83d0  A4      : 0x3ffd7cb4  A5      : 0x3ffd7c94  
A6      : 0x0201a8c0  A7      : 0x0c01a8c0  A8      : 0x8010722c  A9      : 0x3ffcc6e0  
A10     : 0x3ffd79f0  A11     : 0x3ffd83d0  A12     : 0x3ffcc72c  A13     : 0x00000044  
A14     : 0x00000001  A15     : 0x00000006  SAR     : 0x00000010  EXCCAUSE: 0x00000014  
EXCVADDR: 0x00000000  LBEG    : 0x4000c349  LEND    : 0x4000c36b  LCOUNT  : 0x00000000  

ELF file SHA256: 0000000000000000000000000000000000000000000000000000000000000000

Backtrace: 0x00000000:0x3ffcc720 0x40107386:0x3ffcc760 0x40115261:0x3ffcc780 0x4011a1e9:0x3ffcc7c0 0x4011f4a2:0x3ffcc7e0 0x40107d8f:0x3ffcc800 0x4008e0b9:0x3ffcc830

Rebooting...

If I turn off WiFi on my phone, so it does not attempt a connection, the sketch boots fine, but repeats the boot loop seen above as soon as a client tries to connect again.

The only way I have found to get the code to work again (once) is to erase the ESP32's flash with esptool.py --port COM3 erase_flash, then flash the code to the ESP32 again. Again, that only works once, until the board is reset.

Update: After typing up all of the above, I found this, which seems extremely relevant: espressif/arduino-esp32#2025 (comment)

And it seems this suggestion fixes the problem: espressif/arduino-esp32#2025 (comment)