Guides tagged “troubleshooting”
Step-by-step MdmHost guides about troubleshooting, sorted A-Z.
178 guides · page 2 of 9
Email deferred with 421 or 451 errors: what it means and how to fix it
Emails delayed with 421 or 451 temporary errors such as greylisting, rate limiting or try again later? Learn what each means, when to wait and what to fix.
Email not sending from cPanel? How to find and fix the cause
Work out why mail will not send from your cPanel mailbox or website: SMTP settings, ports, authentication, sending limits, blocklists and PHP mail from WordPress.
Enable WordPress debug mode and read the debug log
Turn on WP_DEBUG safely to find the plugin or theme behind an error: log to a private file, read debug.log, check PHP error logs in cPanel and switch it off.
Event Viewer basics on Windows Server
Use Event Viewer on your Windows Server VPS to find errors, unexpected reboots, failed RDP logins and crashing apps, with filters, custom views and useful event IDs.
File upload blocked or deleted by Imunify360? Here is why
Why Imunify360 blocks or removes files right after upload via FTP, File Manager or WordPress, how to confirm it was a malware detection, and what to do next.
Find and fix a WordPress plugin conflict
Track down the plugin or theme behind a WordPress problem with Health Check troubleshooting mode, the half-split method, logs and browser console checks.
Find and fix PHP errors using error_log on cPanel hosting
Locate PHP errors in error_log files and cPanel Errors, read fatal errors and warnings correctly, enable safe debugging and fix the most common PHP messages.
Find and stop processes on Linux: ps, kill, pkill and signals
List and find Linux processes with ps and pgrep, stop them gracefully or forcefully with kill and pkill, understand signals and deal with zombie or stuck processes.
Find website errors with the Plesk Log Browser
Use the Plesk Log Browser to read Apache, Nginx and PHP error logs, filter by status code, watch logs in real time and diagnose 500, 502, 503 and 404 errors.
Fix "413 Request Entity Too Large" on uploads
Fix 413 errors when uploading files: raise client_max_body_size in Nginx, LimitRequestBody in Apache, PHP upload limits, and proxy or CDN limits in front of the server.
Fix "503 Service Unavailable" on LiteSpeed hosting
Find and fix 503 Service Unavailable errors on LiteSpeed cPanel hosting: PHP processes failing to start, resource limits, crashed PHP extensions, and timeouts in long scripts.
Fix "508 Resource Limit Is Reached" on CloudLinux hosting
Why a website shows 508 Resource Limit Is Reached on CloudLinux, how to find which limit was hit in Resource Usage, and the fixes that stop it coming back.
Fix "Allowed memory size exhausted" PHP errors
Understand the PHP fatal error 'Allowed memory size of X bytes exhausted', raise memory_limit on cPanel or a VPS, and find the code that uses too much memory.
Fix "Argument list too long" when deleting or moving many files
Delete, move or process hundreds of thousands of files without hitting 'Argument list too long', using find -delete, find -exec +, xargs and safe batching.
Fix "Bandwidth Limit Exceeded" on a cPanel account
Why a site shows Bandwidth Limit Exceeded, how resellers check and raise the monthly bandwidth limit in WHM, and how to find what is using the traffic.
Fix "Cannot modify header information - headers already sent"
Fix the PHP warning 'headers already sent by output started at file:line': stray whitespace, BOM characters, echo before redirects, closing tags and plugin output.
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 "Cookies are blocked or not supported by your browser" in WordPress
Cannot log in because WordPress says cookies are blocked or not supported? Learn the real causes, from site URL mismatches to caching and stray output, and how to fix them.
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.
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- SSL certificatesFree AutoSSL, Let's Encrypt, paid certificates and HTTPS.41 guides
- CloudLinuxCloudLinux setup and use: LVE limits, CloudLinux Manager, CageFS and PHP/Node.js selectors.31 guides
- LiteSpeedLiteSpeed Web Server, LSCache and the LiteSpeed Cache plugin: install, settings and tuning.35 guides
- Imunify360Malware scanning, firewall and proactive defence with Imunify360.24 guides
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- PleskWebsites, email, databases and settings in the Plesk panel.53 guides
- DirectAdminUsers, domains, email and reseller tools in DirectAdmin.41 guides
- WHMCSBilling, automation, products and client management with WHMCS.52 guides
- Control panelscPanel & WHM, Plesk, DirectAdmin and other panels on your VPS.107 guides
- SecurityKeys, passwords, firewalls and keeping a server patched.138 guides
- Networking & DNSIP addresses, reverse DNS, ports and traffic.72 guides
- Websites & appsWeb servers, WordPress, PHP, Node.js, SSL and app hosting.83 guides
- DatabasesMySQL, MariaDB, PostgreSQL, Redis and MongoDB on a VPS.80 guides
- Billing & accountInvoices, renewals, the client area and your account.9 guides
- TroubleshootingWhen something is not working: checks and fixes.127 guides
- Linux VPSSSH, packages, services and everyday Linux administration.265 guides
- Windows VPS & RDPRemote Desktop, Windows Server settings and Admin RDP tips.73 guides
- Docker & DevOpsContainers, Git deploys, automation, monitoring and backups.82 guides
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