a null character (\x00 or \x{0000}) cannot be used in a Grep pattern

Unicode escapes cannot be used in single-byte Grep searches

a malformed hex or Unicode escape sequence was encountered

“\” not allowed at end of pattern

“?+*” not allowed at beginning of pattern

unmatched “[” or “]”

invalid “[]” range

illegal use of “*?+”

illegal use of “*+”

unmatched parentheses

too many subexpressions

out of memory

pattern too complicated

internal error (2)

internal error (1)

internal error: unexpected token past end of program

internal error: damaged match string

internal error: corrupted opcode

internal error

internal error: corrupted pointers

internal error: corrupted memory

internal error: invalid program

internal error: invalid arguments

A Grep error has occurred: