10 PHP Errors You Should Be Monitoring in Production

In production environments, PHP errors can become serious threats to application stability if not detected promptly. From silent notices to critical failures, each error provides insight into how your system behaves under real-world conditions. Monitoring these errors continuously is not just about fixing bugs. It's about maintaining trust, reliability, and long-term maintainability.

This article covers ten types of PHP errors that demand your attention in production, along with guidance on managing them effectively.

Types of PHP Errors:

1. Fatal Errors (E_ERROR)

2. Parse Errors (E_PARSE)

3. Undefined Variable Errors (E_NOTICE)

4. Deprecation Warnings (E_DEPRECATED)

5. Database Connection Errors

6. Missing File or Include Errors

7. Uncaught Exceptions

8. Permission Denied Errors

9. Memory Limit Errors

10. Slow Scripts and Timeouts

These are the most common PHP errors that tend to surface in production environments each with its own impact and root cause.

Let’s look at them in detail:

1. Fatal Errors (E_ERROR)

These are non-recoverable errors that immediately halt script execution. They often indicate issues like calling undefined functions or exceeding memory limits. In production, they typically result in blank pages or broken endpoints neither of which users tolerate for long.

To avoid being blindsided, these should be captured and reported through a real-time monitoring solution that tracks error spikes and anomalies the moment they occur.

2. Parse Errors (E_PARSE)

Parse errors are caused by syntax issues like missing semicolons, unmatched brackets, or malformed expressions. While these are generally caught during development, rapid patches or overlooked updates can occasionally introduce them into production.

A capable error tracking system helps surface these instantly, especially when integrated into your deployment pipeline for post-deployment observability.

3. Undefined Variable Errors (E_NOTICE)

PHP’s loose typing makes it forgiving, but undefined variable notices can still lead to flawed logic or missing data in rendered views. Left unaddressed, these minor issues can degrade output integrity and frustrate end users.

Monitoring for these notices in production helps identify inconsistent code paths or misaligned data models.

4. Deprecation Warnings (E_DEPRECATED)

Using deprecated functions or features won’t break your app today, but they might tomorrow. These warnings offer a proactive signal to modernize your code before a future PHP upgrade disrupts core functionality.

A monitoring tool that flags deprecated usage allows you to prioritize technical debt reduction based on real-world usage patterns.

5. Database Connection Errors

Connectivity issues with MySQL or other databases often manifest as failed queries or empty responses. Causes can range from network hiccups to exhausted connection pools.

Track database errors centrally to identify recurring issues, correlate failures with application logs, and pinpoint whether the source is infrastructure or application logic.

6. Missing File or Include Errors

Improper use of require or include can result in missing dependencies, especially in large codebases or when autoloaders aren’t used effectively. These errors often cripple specific features without taking down the entire application.

A structured monitoring tool helps tie such errors to request contexts, making troubleshooting faster and more precise.

7. Uncaught Exceptions

Exceptions that escape try-catch blocks can crash request cycles and signal poor error handling or missed edge cases. These are particularly damaging in API backends or job queues.

Global exception tracking with contextual metadata allows teams to investigate root causes rather than symptoms.

8. Permission Denied Errors

PHP scripts may fail to access necessary files or directories if file permissions are misconfigured. These errors commonly appear during file uploads, caching, or when dealing with dynamically created assets.

Consistent visibility into permission-related errors helps you maintain system hygiene and tighten security.

9. Memory Limit Errors

Exceeding PHP’s memory limits results in fatal errors. These often go unnoticed until triggered by specific workloads like large file processing or inefficient loops.

A monitoring platform with performance insights can help correlate memory usage with user actions, allowing smarter optimization efforts.

10. Slow Scripts and Timeouts

Scripts that exceed execution time limits may not log as errors but can degrade user experience or break API contracts. These performance issues are often intermittent and hard to reproduce locally.

Application performance monitoring (APM) tools like Atatus provide a real-time view into slow transactions, helping teams identify latency patterns and optimize bottlenecks.

How to handle errors in PHP?

Handling errors involves a mix of preventive coding (like try-catch blocks), custom error handlers (set_error_handler()), and structured logging. Frameworks like Laravel or Symfony offer centralized exception handling out of the box. Still, visibility into how these errors manifest in production requires a monitoring layer that goes beyond logs and captures full context.

How do I track PHP errors?

Tracking PHP errors in production begins with configuring php.ini to log errors and sending those logs to a centralized system. Rather than sifting through scattered log files, using a comprehensive monitoring tool enables you to automatically capture, categorize, and receive alerts for various PHP issues ranging from fatal crashes to minor warnings.

Conclusion:

Relying on basic log files or manual checks is no longer sufficient for managing modern PHP applications in production. A robust monitoring solution not only highlights what went wrong but where, when, and why. Platforms like Atatus bring together error tracking and performance monitoring in a single dashboard, helping teams respond faster and build more resilient applications.

By focusing on these ten PHP errors, and leveraging the right monitoring tools, you can keep your application running smoothly, no matter what production throws at it.