No NULLs, yet invalid byte sequence for encoding "UTF8": 0x00

I had the same problem using MySQL version 5.0.51 and Postgres version 9.3.4.0. I solved the "invalid byte sequence for encoding "UTF8": 0x00" issue after seeing Daniel Vérité's comment that "mysqldump in postgresql mode will dump null bytes as \0 in strings, so you probably want to search for that sequence of characters."

Sure enough a grep finally revealed the NULL chars.

grep \\\\0 dump.sql

I replaced the NULL chars using the following command

sed -i BAK 's/\\0//g' dump.sql

Postgres was then able to successfully load dump.sql

You can get this error without any NULL byte or any non-ascii character in the file. Example in an utf8 database:

select E'ab\0cd';

will yield:

ERROR: invalid byte sequence for encoding "UTF8": 0x00 HINT: This error can also happen if the byte sequence does not match the encoding expected by the server, which is controlled by "client_encoding".

mysqldump in postgresql mode will dump null bytes as \0 in strings, so you probably want to search for that sequence of characters.

One or more of those character/text fields MAY have 0x00 for its content.

Try the following:

SELECT * FROM rt3 where some_text_field = 0x00 LIMIT 1;

If this returns any single row then try updating those character/text fields with:

UPDATE rt3 SET some_text_field = '' WHERE some_text_field = 0x00;

Afterwards, try another MYSQLDUMP ... ( and PostgreSQL import method ).