pgadmin4.1.1 ERROR,22021,"invalid byte sequence for encoding ""UTF8""

Getting following error in PostgreSQL 9.6.1 DB logs when I tried to view “Scripts=>CREATE Script” on a table in PgAdmin4.1.1 Browser.
PostgreSQL DB has been recently upgraded from version 9.3.9 to 9.6.1 using pg_upgrade utility.

The same browser function worked just fine when pgadmin3 was pointing to PostgreSQL 9.3.9 database (before upgrade).

2017-01-18 07:34:43.364 PST,"user","QA961",5423,"x.x.x.x:64624",587f99b8.152f,4,"idle",2017-01-18 07:24:40 PST,2/92094,0,ERROR,22021,"invalid byte sequence for encoding ""UTF8"": 0x00",,,,,,"
SELECT t.oid,t.tgname AS name, t.xmin, t.*, relname, CASE WHEN relkind = 'r' THEN TRUE ELSE FALSE END AS parentistable,
nspname, des.description, l.lanname, p.prosrc, p.proname AS tfunction,
COALESCE(substring(pg_get_triggerdef(t.oid), 'WHEN (.*) EXECUTE PROCEDURE'),
substring(pg_get_triggerdef(t.oid), 'WHEN (.*) \\$trigger')) AS whenclause,
-- We need to convert tgargs column bytea datatype to array datatype
(string_to_array(encode(tgargs, 'escape'), '\000')::text[])[1:tgnargs] AS tgargs,
(CASE WHEN t.oid <= 13321::oid THEN true ElSE false END) AS is_sys_trigger,
(CASE WHEN tgconstraint != 0::OID THEN true ElSE false END) AS is_constarint,
(CASE WHEN tgenabled = 'O' THEN true ElSE false END) AS is_enable_trigger
FROM pg_trigger t
JOIN pg_class cl ON cl.oid=tgrelid
JOIN pg_namespace na ON na.oid=relnamespace
LEFT OUTER JOIN pg_description des ON (des.objoid=t.oid AND des.classoid='pg_trigger'::regclass)
LEFT OUTER JOIN pg_proc p ON p.oid=t.tgfoid
LEFT OUTER JOIN pg_language l ON l.oid=p.prolang
WHERE NOT tgisinternal
AND tgrelid = 17452::OID
AND t.oid = 18252::OID
ORDER BY tgname;",,,"pgAdmin 4 - DB:QA961"