If you see
WARNING: nonstandard use of \\ in a string literal
HINT: Use the escape string syntax for backslashes, e.g., E'\\'.
Changing all '\\' to E'\\' is a good solution.
However, it will be very tedious if you have a bunch of data. Worst case is when this happen to \n in Linux machine.
A faster fix will be as follow
1. Open postgresql.conf
2. Find #standard_conforming_strings=off. By default, it is commented out by # and set to off
3. Change it to standard_conforming_strings=on
4. Restart postgres
This will cause postgres to treat backslashes as normal character.
If you want postgres to treat backslashes as escape character after turning stardard_conforming_string to on, you must put an E in front. IE, E'this is \\n a string'