Hi,
1_1_Hello_World example from your book: Build web servers esp32….. worked out fine with no problem but when I try the next example 1_2_hello… I just got errors. I uploded the files from data folder. it works fine. now I get erros:

c:/users/raana/.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\lib255\libESP Async WebServer.a(WebAuthentication.cpp.o):(.literal._ZL6getMD5PhtPc+0x4): undefined reference to `mbedtls_md5_starts’
c:/users/raana/.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\lib255\libESP Async WebServer.a(WebAuthentication.cpp.o): in function `getMD5(unsigned char*, unsigned short, char*)’:
C:\Users\raana\OneDrive\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