Advanced Cron Troubleshooting - Intermittent Issues
If you have determined that the cron job is not completing intermittently, but does complete all tasks when invoked via the command line in the previous article, this guide shows how to identify the cause.
We will see how to log the output from the cron.php script to a file using cPanel. Your server may have a different interface for managing cron jobs, or the edit can often be made via the command line. Please refer to your server documentation for more information.
1. Access your WHMCS Admin area. Then, go to Configuration > System Settings > General Settings > Other, or Setup > General Settings > Other for WHMCS 7.10 and earlier.
2. Check Display Errors and then click Save Changes.

3. Log in to the cPanel account that hosts your WHMCS installation
4. Click on Cron Jobs.

5. Edit the cron job command which references the cron.php file:
6. In the Command field, append the following code at the end:
-vvv >> crondebug.txt

7. Click Edit Line
8. Wait until the Time of Day window has passed.
Eg. If the Time of Day setting is 1pm, wait until 2pm.
9. Open the crondebug.txt file which was created in your account root:

10. The file will contain a number of entries from invocation of the cron.php script. Review the file contents to locate the daily automation tasks run. This can be identified by the 24+ tasks queued for execution.
- An error during the execution could look something like this:
WHMCS Automation Task Utility: all
==================================
Queuing Tasks
-------------
Applying "in progress" and "is due" state filters
Task queues ready
Executing Application Queue
---------------------------
Currency Exchange Rates
Product Pricing Updates
Tenant Usage Metrics
[ERROR] WHMCS\Exception\Module\NotServicable: Connection Error: Could not resolve host: fakeservertest(6) in
/home/v80whmcssupport/public_html/whmcs/modules/servers/cpanel/cpanel.php:0
- A successful execution looks like this:
WHMCS Automation Task Utility: all
==================================
Daily Cron Automation Mode
Queuing Tasks
-------------
Applying "in progress" and "is due" state filters
Task queues ready
Executing Application Queue
---------------------------
Currency Exchange Rates
Product Pricing Updates
Invoices
Late Fees
Credit Card Charges
Invoice & Overdue Reminders
Domain Renewal Notices
Cancellation Requests
Overdue Suspensions
Overdue Terminations
Fixed Term Terminations
Inactive Tickets
Delayed Affiliate Commissions
Email Marketer Rules
SSL Sync
Server Usage Stats
Client Status Update
Domain Expiry
Ticket Escalation Rules
Data Retention Pruning
WHMCS Updates
Run Jobs Queue
Sending Daily Cron Digest email
Executing System Queue
----------------------
[OK] Completed
These errors can be used to identify the cause of the cron not completing.
Explanations of common errors are available in our documentation.
WHMCS technical support can advise on the solution to errors which you may encounter, please include the full output when opening a support ticket.