Troubleshooting
When something is not working: checks and fixes.
127 guides · page 2 of 7
Fix "command not found" errors on Linux
Find out why bash says command not found: package not installed, wrong PATH, typos, sudo's secure_path, version-specific binaries and scripts with Windows line endings.
Fix "cPanel license invalid" or licence not found errors
Fix cPanel licence invalid or licence not found errors on a VPS. Check the IP on verify.cpanel.net, open outbound connections, fix DNS and time, and refresh with cpkeyclt.
Fix "Error establishing a database connection" in WordPress
Fix the WordPress database connection error: check wp-config.php credentials, the cPanel database user and privileges, repair tables and rule out server limits.
Fix "fork: Resource temporarily unavailable" on Linux
Fix Linux errors like fork: retry: Resource temporarily unavailable and Cannot allocate memory by checking process limits (nproc), systemd TasksMax, pid_max, runaway processes and memory.
Fix "Job for service failed" when a systemd service won't start
Diagnose systemd services that fail to start: read status and journal output, decode exit codes like 203/EXEC and 217/USER, test configs, and fix restart loops.
Fix "Maximum execution time exceeded" PHP errors
Fix the PHP fatal error 'Maximum execution time of 30 seconds exceeded': raise max_execution_time correctly, align web server timeouts and move long tasks out of web requests.
Fix "No space left on device" on Linux
Free disk space fast when Linux reports 'No space left on device': find what fills the disk, clear logs and caches safely, and fix inode exhaustion and deleted-but-open files.
Fix "No space left on device" when the disk isn't full (inodes)
Linux says no space left on device but df -h shows free space? Use df -i to confirm inode exhaustion, find the folder with millions of files and clean it up safely.
Fix "Permission denied" errors on Linux
Work out why Linux says Permission denied: missing execute bits, directory permissions, wrong owner, sudo needed, noexec mounts, SELinux or AppArmor, with a fix for each.
Fix "permission denied" on the Docker socket
Fix the "permission denied while trying to connect to the Docker daemon socket" error. Add your user to the docker group, apply it without rebooting, and understand the security trade-off versus sudo.
Fix "Read-only file system" errors on a Linux VPS
Find out why Linux remounted a disk read-only, check kernel logs for disk or filesystem errors, run fsck safely from rescue mode and recover writes without losing data.
Fix "Remote Desktop can't connect to the remote computer"
Check the server is running, test the RDP port, rule out network blocks and repair Remote Desktop settings from the browser console.
Fix "SSL certificate problem: unable to get local issuer certificate"
Fix TLS verification errors when your server, PHP, curl, Node.js or Python calls HTTPS APIs: outdated CA bundles, missing intermediate certificates, wrong clock and proxies.
Fix "target is busy" and "Device or resource busy" on Linux
Unmount a disk that reports target is busy, find which processes hold files open with lsof and fuser, and handle busy files, swap and LVM devices safely.
Fix "Temporary failure in name resolution" on Linux
Fix DNS lookups failing on a Linux server: check resolv.conf and systemd-resolved, set working nameservers, test with dig, and rule out firewall and network problems.
Fix "There has been a critical error on this website"
Recover from the WordPress critical error message: use the recovery mode email, find the failing plugin or theme in the logs and get back into the dashboard.
Fix "Too many open files" errors on Linux
Understand file descriptor limits, check what a process is allowed and using, and raise limits correctly for systemd services, Nginx, MySQL, Node.js and user sessions.
Fix "Your credentials did not work" in Remote Desktop
Fix rejected RDP logins: username format, the right password, stale saved credentials, account lockout and Remote Desktop permissions.
Fix 403 Forbidden errors on cPanel hosting
Solve 403 Forbidden on a cPanel website: missing index file, wrong permissions, .htaccess deny rules, IP Blocker entries, hotlink protection or ModSecurity blocks.
Fix 403 Forbidden in Nginx
Nginx returns 403 Forbidden when it will not serve a file or folder. Work through the usual causes, from a missing index file to permissions, deny rules and SELinux.
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