Phase 1: Error Classification 🚨 Classification: Fatal error / undefined function. The PHP runtime reports: Call to undefined function wc_get_product() This means PHP reached the call: wc_get_product(123); but the function was not available in the current execution context. This is not merely a warning or notice. Execution stops at this point. --- Phase 2: Exact Error Interpretation 🧠 The important parts are: Failing function: wc_get_product() File: custom-shop.php Line: 42 Calling component: Custom Shop plugin Expected provider: WooCommerce Failure type: Function unavailable when called The error does not automatically prove that WooCommerce is broken. The immediate technical fact is: > The Custom Shop plugin attempted to call a WooCommerce function at a time when that function was unavailable. --- 🔗 Phase 3: Execution Path The simplified execution path is: WordPress bootstrap ↓ Plugin loading ↓ Custom Shop plugin ↓ Registers custom_display_product() ↓ WordPress fires init ↓ custom_display_product() ↓ wc_get_product(123) ↓ ❌ Function unavailable ↓ Fatal Error The important clue is: add_action('init', 'custom_display_product'); The function is being executed during the init hook. --- 🧩 Phase 4: Component Analysis The directly affected component is: Custom Shop plugin WooCommerce is a dependency because the code calls: wc_get_product() The stack trace showing custom-shop.php does not by itself prove that Custom Shop contains a bug. Possible dependency-related explanations need to be investigated. --- 🧪 Phase 5: Root-Cause Hypotheses Hypothesis 1: WooCommerce is inactive 🔌 Status: Plausible If WooCommerce is inactive, its functions will not be available. Supporting evidence: wc_get_product() belongs to WooCommerce. The failing plugin depends on WooCommerce. Missing evidence: Whether WooCommerce is actually active when the error occurs. Verification: Check: WordPress Admin → Plugins → Installed Plugins → WooCommerce --- Hypothesis 2: Custom Shop executes before WooCommerce is loaded ⏱️ Status: Strongly supported as a possibility The plugin executes its callback on: init However, simply using init does not guarantee that every dependency is correctly initialized. The dependency should be explicitly checked rather than assumed. For example: if ( function_exists( 'wc_get_product' ) ) { $product = wc_get_product(123); } This prevents the immediate fatal error, although it may not be the complete architectural fix. --- Hypothesis 3: WooCommerce is missing or incompatible 🔄 Status: Plausible but not confirmed The supplied versions are: WordPress 6.8 PHP 8.2 WooCommerce 9.8 Nothing in the supplied error alone proves a PHP 8.2 incompatibility. Likewise, the error does not establish that WooCommerce 9.8 is incompatible with WordPress 6.8. Those assumptions should not be made without compatibility evidence. --- Hypothesis 4: Another plugin disabled or altered WooCommerce loading 🧩 Status: Weak / requires evidence Possible in a complex WordPress installation, but there is currently no evidence showing another plugin is interfering. This should not be the first diagnosis. --- ⚖️ Phase 6: Evidence Assessment Hypothesis Assessment WooCommerce inactive Plausible WooCommerce unavailable when callback runs Strongly supported PHP 8.2 incompatibility Unsupported by current evidence WordPress 6.8 incompatibility Unsupported by current evidence Another plugin interference Weak Database problem Unsupported API failure Unsupported Memory exhaustion Unsupported --- 🎯 Phase 7: Strongest Diagnosis The strongest diagnosis from the supplied evidence is: > Custom Shop calls the WooCommerce function wc_get_product() without establishing that WooCommerce's API is available in the current execution context. The exact underlying reason still needs verification. The most important things to establish are: 1. Is WooCommerce active? 2. Is WooCommerce loaded when custom_display_product() executes? 3. Does the error occur only when WooCommerce is inactive? 4. Is there a plugin-loading or dependency-order problem? --- 🔬 Phase 8: Verification A safe diagnostic version would be: function custom_display_product() { if ( ! function_exists( 'wc_get_product' ) ) { error_log( 'Custom Shop: WooCommerce API is unavailable.' ); return; } $product = wc_get_product(123); if ( ! $product ) { error_log( 'Custom Shop: Product 123 could not be loaded.' ); return; } echo esc_html( $product->get_name() ); } add_action( 'init', 'custom_display_product' ); This diagnostic does two useful things: prevents the immediate fatal error records whether the WooCommerce function is unavailable It also checks whether product 123 actually exists. --- 🛠️ Phase 9: Recommended Fix The permanent fix should depend on the verification result. If WooCommerce is intentionally required The plugin should declare WooCommerce as a dependency and avoid running its WooCommerce-specific functionality when WooCommerce is unavailable. A basic guard can be: if ( ! class_exists( 'WooCommerce' ) ) { return; } or: if ( ! function_exists( 'wc_get_product' ) ) { return; } The appropriate dependency mechanism depends on how the plugin is structured and how it supports WordPress/WooCommerce versions. Important ⚠️ Simply adding: if ( ! function_exists( 'wc_get_product' ) ) { return; } prevents the fatal error, but it may only be a defensive fix. If WooCommerce should always be available, the real issue may be the plugin's dependency/loading architecture. --- 🩹 Phase 10: Temporary Mitigation Temporary mitigation: Prevent the callback from executing when WooCommerce is unavailable. function custom_display_product() { if ( ! function_exists( 'wc_get_product' ) ) { return; } $product = wc_get_product(123); if ( ! $product ) { return; } echo esc_html( $product->get_name() ); } Risk The fatal error disappears, but the product name will not be displayed if WooCommerce is unavailable. Therefore this should not automatically be considered the permanent solution. --- 🔐 Phase 11: Security & Code Quality The original code contains: echo $product->get_name(); The safer output approach is: echo esc_html( $product->get_name() ); This is separate from the reported fatal error, but it is a relevant output-safety improvement. The code should also verify that the product object exists before calling: $product->get_name() --- 🧪 Phase 12: Regression Tests After fixing the dependency handling, test: 1. WooCommerce active + product exists Product name displays. 2. WooCommerce active + product does not exist No fatal error. 3. WooCommerce inactive No fatal error. 4. Logged-in administrator Verify expected behavior. 5. Logged-out visitor Verify expected behavior. 6. Plugin activation Custom Shop should not crash WordPress if WooCommerce is unavailable. 7. Plugin deactivation No references to unavailable WooCommerce functions should execute. 8. PHP 8.2 Verify the original workflow. 9. Production-like staging environment Test with the actual plugin/theme combination. --- 🚀 Phase 13: Production Deployment Before production: 💾 Back up the site. 🧪 Apply the change on staging first. 🔍 Reproduce the original failure. 🔧 Apply the dependency fix. 🧪 Run the regression tests. 🧹 Clear relevant WordPress/cache layers if necessary. 📋 Check debug.log and server logs. ↩️ Keep a rollback copy of the modified plugin code. 🚀 Deploy only after staging behaves correctly. Do not edit WordPress core files. Do not directly modify third-party plugin files unless there is no supported alternative and the change is controlled. --- ✅ Phase 14: Final Engineering Conclusion Error: Call to undefined function wc_get_product() Type: Fatal error / undefined function. Affected component: Custom Shop plugin. Dependency: WooCommerce. Immediate failure: The plugin calls a WooCommerce function that is unavailable at execution time. Strongest diagnosis: The Custom Shop code does not adequately establish that the WooCommerce API is available before using it. Confirmed underlying reason: Not yet confirmed. Most important verification: Determine whether WooCommerce is inactive, unavailable during the callback, or incorrectly loaded. Temporary mitigation: Guard the WooCommerce function call. Permanent fix: Correct the plugin's WooCommerce dependency/loading architecture based on the verified cause. Security improvement: Escape the product name with esc_html() before output. Production approach: Test on staging, verify the dependency behavior, run regression tests, then deploy with rollback available.