Understanding Merchant Center Diagnostics: Fix Warnings & Errors Fast

If you're running Google Shopping ads or managing an online store, you've probably come across the Google Merchant Center Diagnostics tab. It's the place where Google flags everything that might be wrong with your product listings  from missing product data to serious policy violations. But let’s be honest, staring at those red and yellow alerts can be overwhelming, especially if you're not sure what they mean or how to fix them.

The good news? You’re not alone, and most of these issues can be resolved quickly once you understand what you’re dealing with. Merchant Center diagnostics may look technical at first glance, but they follow a simple pattern. Errors are the most urgent and can result in disapproved products. Warnings are less severe but can still limit visibility. Then there are notifications, which are more like friendly suggestions.

This blog is your go-to guide for decoding those alerts, fixing them step-by-step, and keeping your Merchant Center in good standing. We’ll break down the most common errors and warnings, show you exactly how to resolve them, and give you practical tips to prevent future problems. Whether you’re new to Merchant Center or just tired of getting disapprovals you don’t understand, this guide will help you take control.

By the end of this post, you’ll know how to:

• Read and understand your diagnostics tab

• Prioritize what needs fixing

• Avoid account suspensions

• Automate your product feed to reduce future errors

Let’s get into it.

Understanding Merchant Center Diagnostics

What Are Errors, Warnings & Notifications?

When you open the Diagnostics tab in Google Merchant Center, you’ll see three types of alerts: Errors, Warnings, and Notifications. Each one tells you something different about the health of your product listings.

• Errors are the most serious. These mean your products are disapproved and not eligible to appear in Google Shopping ads until the issue is fixed. For example, if your product is missing a required attribute like a price or GTIN, it won’t be shown at all.

• Warnings are important, but not immediately disqualifying. They let you know your product is still approved, but might not perform as well or could be disapproved in the future if not corrected. For instance, using a generic product title like “Best Shoes” might trigger a warning.

• Notifications are more like suggestions. They don’t affect product visibility but give you tips to improve the quality or compliance of your listings. Think of these as maintenance alerts rather than urgent issues.

Understanding the difference between these three levels will help you focus your time and energy where it matters most.

Where to Find & How to Read the Diagnostics Tab

To access your Diagnostics tab, log into your Google Merchant Center account. You’ll find it in the left-hand navigation menu under “Products” > “Diagnostics”. Once inside, you'll see a summary of account-level, feed-level, and item-level issues.

Here’s how to break it down:

• Use the tabs (Account, Feeds, Items) to locate exactly where the issue is.

• Click into specific error or warning messages to view affected products, the type of issue, and Google’s recommendation for a fix.

• Pay attention to the “last detected” date it helps you track whether the issue is recurring or resolved.

You can also download a report or export the list of affected items to share with your developer or upload fixes via a feed.

This diagnostics dashboard is your command center. Understanding how to navigate it and interpret the messages correctly is your first step in fixing problems fast and avoiding product disapprovals.

Fixing the Most Common Errors and Warnings

Data Feed Errors (Titles, GTIN, Price, Availability)

Most Merchant Center issues stem from basic product data problems. These include missing or incorrect titles, GTINs (Global Trade Item Numbers), prices, or availability status.

Common examples:

• A product with no GTIN or incorrect GTIN format.

• Price in the product feed doesn't match the price on your website.

• Product marked “in stock” in Merchant Center but out of stock on the site.

How to fix it:

• Use tools like Google’s Feed Rules to correct or map data.

• Double-check that your feed matches your website exactly, especially for price and availability.

• If you're using Shopify or WooCommerce, install a reliable feed management app that syncs automatically.

• For GTINs, make sure you're using valid and category-appropriate codes. Google may disapprove items missing GTINs in certain industries.

Keep in mind: even small mismatches (like a currency symbol or number format) can cause disapprovals.

Policy Violations & Misrepresentation Issues

This is one of the trickiest areas because it often leads to suspensions without a warning. Google is strict about trust, transparency, and consistency.

Policy violations include:

• Incomplete or missing return/refund policies.

• Misleading product claims or price baiting.

• Using logos or brand names you don’t own.

Misrepresentation examples:

• Listing fake discounts (e.g., “50% off” when no original price exists).

• Not showing accurate shipping/tax info.

• Having different product specs on your site compared to the feed.

Fixing tips:

• Ensure your About, Contact, and Return Policy pages are easily accessible and complete.

• Stick to transparent pricing and product descriptions.

• If you’re suspended for misrepresentation, fix all violations first and then submit a Re-review request from the Diagnostics tab.

Timeline to Fix & Request a Review

When Google flags an issue, you’re usually given a window to resolve it before your products are disapproved or your account is suspended.

• For warnings, you often have up to 28 days to make corrections.

• For errors, products are immediately disapproved until the issue is fixed.

• For policy violations, suspensions may happen right away  no grace period.

Once you've corrected the problem:

1. Go to the Diagnostics tab and click on the issue.

2. Fix the feed or website problem as outlined.

3. Submit a Re-review request directly through the interface.

Re-review tips:

• Don’t submit multiple times  wait for the full review cycle (usually 3–5 business days).

• Make sure all listed violations are fully resolved before requesting a review.

• Be patient and check back in your Diagnostics tab for the updated status.

Pro Tips to Prevent Future Merchant Center Issues

Set Up Automation & Feeds Correctly

One of the best ways to avoid Merchant Center errors is to automate your product feed and keep it in sync with your website. Manual uploads or CSV files are more prone to human error and outdated data.

Automation tips:

• If you're using Shopify, install the official Google & YouTube app to sync your product catalog automatically.

• On WooCommerce, plugins like Product Feed Pro or CTX Feed allow scheduled feed updates and customizable attributes.

• Use Google Content API for Shopping for large inventories  it pushes real-time updates for price and availability changes.

• Enable Automatic Item Updates (AIU) in Merchant Center. This allows Google to update your product’s price and availability automatically by crawling your site if a mismatch is detected.

By automating your feeds, you're reducing the chances of price mismatches, outdated availability, and missing data  three of the most common causes of product disapprovals.

Run Weekly Diagnostics Audits

Even with automation, things can still go wrong  which is why a weekly audit routine is a smart habit.

Here’s a quick checklist to follow every week:

• Open your Merchant Center Diagnostics tab and review Errors, Warnings, and Notifications.

• Click through item-level details to identify recurring issues.

• Check if new products have been disapproved or are missing attributes.

• Confirm that your product feed is syncing as scheduled  especially after making changes to your website.

• Review your site’s shipping, tax, and return policies to ensure they are up-to-date and visible.

Extra tip: Set calendar reminders for audits or assign the task to a team member. A 15-minute check each week can save you from days of lost sales due to unexpected suspensions.

Conclusion

Google Merchant Center Diagnostics may seem intimidating at first, but once you understand how it works, it becomes a powerful tool to keep your product listings clean, compliant, and high-performing.

We’ve covered the key differences between errors, warnings, and notifications, and how each one impacts your listings. You’ve also learned how to fix the most common issues  from product data mismatches to serious policy violations  and how to request a re-review once everything is corrected.

Most importantly, you now know how to stay ahead of future issues with automation tools and a simple weekly audit checklist. With these best practices in place, you’ll spend less time firefighting and more time growing your e-commerce business.

Don’t wait until a warning turns into a suspension. Make it a habit to check your diagnostics tab regularly and keep your product data fresh, accurate, and policy-compliant.

Need help? Download our free Merchant Center Troubleshooting Checklist or get in touch if you want a hands-on review of your setup.