Permission Denied When Writing Files

1. Target directory owned by different user, application user lacks write permission
2. Directory permissions too restrictive (755 prevents write by non-owner)
3. Parent directory doesn't have execute bit, preventing access to subdirectories
4. SELinux or AppArmor policies blocking file access
5. Disk full, preventing new writes despite having permissions

Check permissions: ls -la /path/to/dir. Change if needed: chmod 755 or chown to correct user. Ensure application user is owner or in group: chown app:app /logs. Create directories with correct permissions at startup. Use world-writable temp directories (/tmp) if needed. Run with sudo or correct user: sudo -u app java -jar app.jar