BUG #17266: could not truncate file "base/126370/130666" to 0 blocks: Permission denied

The following bug has been logged on the website:

Bug reference:      17266
Logged by:          Adam Santiaji
Email address:      adam@drose-consulting.com
PostgreSQL version: 12.0
Operating system:   Window Server 2016 Standard
Description:

from log postgreSQL i found this error log from 2021-11-01
2021-11-01 08:55:47.110 +07 [6860] ERROR:  could not truncate file
"base/126370/130666" to 0 blocks: Permission denied
2021-11-01 08:55:47.110 +07 [6860] CONTEXT:  automatic vacuum of table
"ykkap.public.imw_t_thread"
2021-11-01 08:58:47.124 +07 [9604] ERROR:  could not truncate file
"base/126370/127251" to 0 blocks: Permission denied
2021-11-01 08:58:47.124 +07 [9604] CONTEXT:  automatic vacuum of table
"ykkap.public.im_async_task_info"

and when i try to backup database on 2021-11-02 it show error
2021-11-02 21:21:36.970 +07 [10252] ERROR:  missing chunk number 0 for toast
value 250117 in pg_toast_127251

what does it mean Permission denied? is it cause of permission access from
windows?
how to avoid this error log in future?