Failed to execute pg_dump

Hi Everyone

I have a test server which is running Centos7, PHP 7.1.13, PostgreSQL 9.6.5
and phpPgAdmin 5.1

When I went to dump a database I received the following error:

Export error: Failed to execute pg_dump (given path in your
conf/config.inc.php : /opt/rh/rh-postgresql96/root/usr/bin/pg_dump). Please,
fix this path in your configuration and relog.

The path /opt/rh/rh-postgresql96/root/usr/bin/pg_dump is valid.

I have checked the /user/share/phpPgAdmin/conf/config.inc.php which appears
to be the configuration file mentioned in the error message and I can't see
any obvious issues.

I searched this problem in the mailing list but could not find any recent
results. I did find an older result which said to correct the path in the
config file, but that looks right to me.

Any ideas?

Thanks