Hello,
I’m currently at the ‘1_2_Hello_World_WS_SPIFFS’ example. First I typed/copied all code manually (helps me to memorize things better), but I ran into an error during the build process. To eliminate possible type errors e.g. I downloaded all file from the link in your ebook (page 185) and I get the same error message. I couldn’t figure out so far what I did wrong and the error message is not very helpful to me. I would very much appreciate any help on this matter. Thanks in advance.
 
Best,
Peter
Linking .pio\build\esp32doit-devkit-v1\firmware.elf
c:/users/user/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/8.4.0/../../../../xtensa-esp32-elf/bin/ld.exe: .pio\build\esp32doit-devkit-v1\libe96\libESP Async WebServer.a(WebAuthentication.cpp.o):(.literal._ZL6getMD5PhtPc+0x4): undefined reference to `mbedtls_md5_starts’
c:/users/user/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/8.4.0/../../../../xtensa-esp32-elf/bin/ld.exe: .pio\build\esp32doit-devkit-v1\libe96\libESP Async WebServer.a(WebAuthentication.cpp.o): in function `getMD5(unsigned char*, unsigned short, char*)’:
C:\Users\User\Documents\PlatformIO\Projects\1_2_Hello_World_WS_SPIFFS/.pio/libdeps/esp32doit-devkit-v1/ESP Async WebServer/src/WebAuthentication.cpp:73: undefined reference to `mbedtls_md5_starts’
collect2.exe: error: ld returned 1 exit status
*** [.pio\build\esp32doit-devkit-v1\firmware.elf] Error 1
================================================= [FAILED] Took 154.48 seconds =================================================
 
*  The terminal process “C:\Users\User\.platformio\penv\Scripts\platformio.exe ‘run'” terminated with exit code: 1.
 *  Terminal will be reused by tasks, press any key to close it.