This article describes one possible reason for the below commit error.

user@switch# commit

error: /config/juniper.conf+: was not properly closed: Unknown error: 0

error: configuration check-out failed: commit to file failed during export to /config/juniper.conf+

This error message is being raised when attempting to commit configuration changes. The configuration will not be committed after such errors.

Deleting juniper.conf+ from /config does not help.

https://supportportal.juniper.net/s/article/Junos-Commit-error-error-commit-failed-commit-to-file-failed-during-export-to-config-juniper-conf

1. Check system storage:

user@switch> show system storage | match /config

/dev/da0s4d       116M    115M   -9.2M   109% /config

2. Check /config for any large files. In this case case auto_image_upgrade.conf was very large. 

user@switch> start shell

%

% ls -al /config | grep auto_image_upgrade

-rw-r--r--  1 root wheel 120913920 Dec 31 2022 auto_image_upgrade.conf

3. Delete auto_image_upgrade.conf

root@switch:RE:0% rm auto_image_upgrade.conf