Postgresql won't restore dump

Question

I've been trying to restore dump file dump-postgres-202010121008.sql but it won't be restored, I've tried the following restoration methods but it seems of no use:

Method1: using pgAdmin 4

I've tried the pg_restore method with the following inputs:

Format: custom or tar

File name: path to the file

Number of jobs: empty

Role name: postgres

When i click restore, i get a Failed(exit code: 1) with the following error message:

pg_restore: error: input file does not appear to be a valid archive

I've also tried Query Tool > open file, still i got an error File type not supported.

Method 2: using command line

I've tried pg_restore command on terminal but it returned pg_restore: error: input file does not appear to be a valid archive

I've also tried the following commands:

su postgres
psql postgres
\i dump-postgres-202010121008.sql

However i got this log:

psql:dump-postgres-202010121008:42473: error: invalid command \��0�8�ӛӣ��X�H6����.�y�:���e�ne��Pc�9x@%"˔U�rV7M=�
psql:dump-postgres-202010121008.sql:42474: error: invalid command \�T����kW:����Һ�-kL
psql:dump-postgres-202010121008.sql:42484: error: invalid command \M�LJ,�ϐ}�c,J�-�)ATo▒�HJ��+w
psql:dump-postgres-202010121008.sql:783003: ERROR:  invalid byte sequence for encoding "UTF8": 0xea 0xab 0x7a

Any help would be appreciated, thank you.