Cannot open any notes #384

Describe the bug

I can no longer open any notes after upgrading to Nextcloud 16.0.3 (then later upgraded to 16.0.4)

Looking at the JSON response it looks like this

{"JSON":{"etag":"45c5269c51a890deaf1d02139403a959","modified":null,"title":"Fusion project","category":"statkraft","content":"Error: (Fusion project.txt) An exception occurred while executing 'INSERT INTO "oc_file_locks" ("key", "lock", "ttl") VALUES(?, ?, ?) ON CONFLICT DO NOTHING' with params ["files\/3f12ddc0287423160f601fa2e1029d01", 1, 1569178240]:\n\nSQLSTATE[42601]: Syntax error: 7 ERROR: syntax error at or near "ON"\nLINE 1: ..._locks" ("key", "lock", "ttl") VALUES($1, $2, $3) ON CONFLIC...\n ^","favorite":false,"error":true,"errorMessage":"Error: (Fusion project.txt) An exception occurred while executing 'INSERT INTO "oc_file_locks" ("key", "lock", "ttl") VALUES(?, ?, ?) ON CONFLICT DO NOTHING' with params ["files\/3f12ddc0287423160f601fa2e1029d01", 1, 1569178240]:\n\nSQLSTATE[42601]: Syntax error: 7 ERROR: syntax error at or near "ON"\nLINE 1: ..._locks" ("key", "lock", "ttl") VALUES($1, $2, $3) ON CONFLIC...\n ^","id":6234}}

To Reproduce
Steps to reproduce the behavior:

1. Go to Notes app in the webpage
2. Click any note
3. Note does not open, but at the top of the page an error message is seen

Expected behavior
That I can open a note

Server (please complete the following information):

• Notes app version: 3.0.3
• Nextcloud version: 16.0.4
• OS: entos-release-7-6.1810.2.el7.centos.x86_64
• Web server: Not known. Managed by hosting provider. Probably Apache
• PHP version: 7.1
• Database: PostgreSQL 9.4.24 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-36), 64-bit

Client (please complete the following information):

• Browser (incl. version): Firefox 69.0. Also newer Chrome
• OS: Linux and Windows.

This mostly looks like server side issue.

Log files