For the past two days, I've been trying to set up an ESP8266WebServer to serve my static web app files from SPIFFS. But as soon as I make a call to `serveStatic`, the ESP crashes. This is the exact code I'm running:
#include <FS.h>
#include <ESP8266WebServer.h>
ESP8266WebServer s;
void setup() {
Serial.begin(115200);
if(!SPIFFS.begin()){
Serial.println("An Error has occurred while mounting SPIFFS");
return;
}
s.serveStatic("/", SPIFFS, "/static/");
s.begin();
}
void loop() {
s.handleClient();
}
I know that this is example does not allow me to access the files in any way because I don't have WiFi configured, but this is enough for me to crash the ESP. This is the error that I keep seeing:
```SDK:2.2.2-dev(38a443e)/Core:2.6.3=20603000/lwIP:STABLE-2_1_2_RELEASE/glue:1.2-16-ge23a07e/BearSSL:89454af
SPIFFSImpl: allocating 512+240+1400=2152 bytes
SPIFFSImpl: mounting fs @100000, size=2fa000, block=2000, page=100
SPIFFSImpl: mount rc=0
Fatal exception 28(LoadProhibitedCause):
epc1=0x4021407a, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000
Exception (28):
epc1=0x4021407a epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000
>>>stack>>>
ctx: cont
sp: 3ffffca0 end: 3fffffc0 offset: 01a0
3ffffe40: 3ffefaf8 00000000 3ffffea0 402127b1
3ffffe50: 00000001 ffffffff 4020a9dc 00000000
3ffffe60: 3ffe8304 00000000 0000000a 40216e21
3ffffe70: 402497e1 00000000 00000000 4020b414
3ffffe80: 3ffffee0 3ffffed0 00000008 402497e3
3ffffe90: 402497e2 3ffe8304 3ffefaf8 402171ec
3ffffea0: 00000000 ffffffff 00000000 00000000
3ffffeb0: 00000001 00000041 3f302073 40212d8e
3ffffec0: 3ffffee0 3ffffed0 00000004 40209c90
3ffffed0: 3fffff10 00000000 00000017 3fff0580
3ffffee0: 00308658 3fffff20 3ffef85c 4020a3e9
3ffffef0: 000018c0 3ffee6b0 00000000 40208120
3fffff00: 3fffff60 3fffff50 00000014 00000001
3fffff10: 00000009 00000001 00000001 40207c65
3fffff20: 40100b04 00001000 00002000 3fff0580
3fffff30: 3ffe8658 402497a4 3ffe8304 40212d8e
3fffff40: 3fffff60 3fffff50 00000004 40100476
3fffff50: 3ffe8658 3ffe8658 3ffe865f 00000000
3fffff60: 00000000 00000000 3fff056c 4020ffa5
3fffff70: 3fffdad0 3ffee690 3fff056c 40201325
3fffff80: 3ffe865f feefeffe feefeffe feefeffe
3fffff90: feefeffe feefeffe feefeffe 3ffee610
3fffffa0: 3fffdad0 00000000 3ffee5d0 40206aa0
3fffffb0: feefeffe feefeffe 3ffe84f4 40101245
<<<stack<<<
ets Jan 8 2013,rst cause:2, boot mode:(3,6)
load 0x4010f000, len 1392, room 16
tail 0
chksum 0xd0
csum 0xd0
v3d128e5c
~ld
```
I have also analyzed the stack trace using ESP exception decoder, which didn't get me any further though. Here is the output of that tool:
```
Exception 28: LoadProhibited: A load referenced a page mapped with an attribute that does not permit loads
PC: 0x4021407a: pgm_read_byte_inlined at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/sys/xtensa/sys/pgmspace.h line 72
EXCVADDR: 0x00000000
Decoding stack results
0x402127b1: _printf_i at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf_i.c line 226
0x4020a9dc: spiffs_object_find_object_index_header_by_name_v(spiffs*, spiffs_obj_id, spiffs_block_ix, int, void const*, void*) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/spiffs/spiffs_nucleus.cpp line 1664
0x40216e21: __sfputs_r at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf.c line 433
0x4020b414: spiffs_obj_lu_scan(spiffs*) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/spiffs/spiffs_nucleus.cpp line 439
0x402171ec: _vfprintf_r at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/nano-vfprintf.c line 667
0x40212d8e: printf at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/printf.c line 61
0x40209c90: SPIFFS_mount(spiffs*, spiffs_config*, u8_t*, u8_t*, u32_t, void*, u32_t, spiffs_check_callback) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/spiffs/spiffs_hydrogen.cpp line 138
0x4020a3e9: SPIFFS_stat(spiffs*, char const*, spiffs_stat*) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/spiffs/spiffs_hydrogen.cpp line 769
0x40208120: spiffs_impl::SPIFFSImpl::_tryMount() at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/spiffs_api.h line 320
0x40207c65: spiffs_impl::SPIFFSImpl::exists(char const*) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/spiffs_api.cpp line 80
0x40100b04: get_poisoned(void*, size_t) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/umm_malloc/umm_poison.c line 112
0x40212d8e: printf at /home/earle/src/esp-quick-toolchain/repo/newlib/newlib/libc/stdio/printf.c line 61
0x40100476: pvPortMalloc(size_t, char const*, int) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/heap.cpp line 267
0x4020ffa5: fs::FS::exists(char const*) at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/FS.cpp line 363
0x40201325: setup() at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/libraries/ESP8266WebServer/src/detail/RequestHandlersImpl.h line 75
0x40206aa0: loop_wrapper() at /Users/alex/Library/Arduino15/packages/esp8266/hardware/esp8266/2.6.3/cores/esp8266/core_esp8266_main.cpp line 177
```
These are my settings in the Arduino IDE:
[![Sketch settings in IDE][1]][1]
[1]: https://i.sstatic.net/T2XSa.jpg
To flash the data to the ESP, im using the latest version of this tool for the Arduino-IDE: https://github.com/esp8266/arduino-esp8266fs-plugin
I'm probably making a stupid mistake but I've been scratching my head for hours now and can't see where the issue could be. Any help would be greatly appreciated!
**EDIT #1:**
The data is definitely available on the ESP, since this snippet works fine:
```
#include <FS.h>
#include <ESP8266WebServer.h>
ESP8266WebServer s;
void setup() {
Serial.begin(115200);
if(!SPIFFS.begin()){
Serial.println("An Error has occurred while mounting SPIFFS");
return;
}
/*s.serveStatic("/", SPIFFS, "/static/");
s.begin();*/
}
void loop() {
//s.handleClient();
delay(5000);
File f = SPIFFS.open("/static/index.html", "r");
String s = f.readString();
Serial.println(s);
f.close();
}
```