Received this error on compile after update:
Core 4.3.4
Assembler messages:
Internal error in expression_maybe_register at /builds/idf/crosstool-NG/.build/HOST-i686-w64-mingw32/xtensa-esp32-elf/src/binutils/gas/config/tc-xtensa.c:1939.
Please report this bug.
problem within this code. Compile works after comment it out. But took some time to find it 
void (rvect)(void) = (void ()(void))0x80000000;
rvect();
this was old code left from an AT32* Project but at least it compiled before.