Shopify makes it relatively easy to build and customize an online store, but custom themes, apps, Liquid code, CSS, and JavaScript can sometimes create unexpected problems.

A store may look completely normal on desktop but appear broken on mobile. A Shopify Liquid error may suddenly appear after a theme edit. An Add to Cart button may stop working, or a section that was previously visible may disappear.

These problems can be frustrating because the visible symptom isn't always the actual cause.

For example, a broken product page might be caused by a Liquid error, CSS conflict, JavaScript error, app integration, or a recent theme customization.

Shopify's own troubleshooting documentation recommends checking whether the problem is specific to the current theme, reviewing recent code changes, testing other devices/browsers, and checking recently installed or updated apps.

In this guide, we'll look at 7 common Shopify theme bugs, what causes them, and how to troubleshoot them without randomly changing your store's code.

1. Shopify Liquid Errors

One of the most common Shopify theme problems is a Liquid error.

Liquid is Shopify's templating language and is used throughout Shopify themes to display dynamic content.

A small mistake in Liquid code can cause a section, template, or even part of the storefront to stop working correctly.

Common causes include:

Incorrect Liquid syntax
Missing closing tags
Incorrect variables
Broken snippets
Invalid objects or filters
Recently edited theme code
Custom Liquid sections
Third-party code

Shopify's theme editor can show errors related to invalid Liquid or HTML, and Shopify recommends reviewing the .liquid file associated with the error and checking recent changes.

How to troubleshoot a Shopify Liquid error

Start by identifying the file mentioned in the error.

Then check:

What was changed recently?
Is the Liquid syntax correct?
Are all tags properly closed?
Is the snippet being called correctly?
Is the variable available in that location?
Did the error begin after installing an app or adding custom code?

Don't immediately replace the entire section.

A small piece of incorrect Liquid can sometimes cause a much larger visible problem.

Still getting a Liquid error?

If you have already tried fixing the code and the error is still present, you can get help fixing a Shopify Liquid or theme issue on Fiverr.

2. Shopify Sections Not Showing or Working Correctly

Shopify themes are built around sections and blocks that allow merchants to customize their storefront.

Sometimes a section can suddenly:

Disappear
Stop loading
Display incorrect content
Show on desktop but not mobile
Work on one template but not another
Display incorrectly after a theme update

This can happen because of theme code, section settings, template configuration, or customizations.

Shopify recommends determining whether the problem exists only in the current theme or across other themes. If the issue appears only in the current theme, theme code or customization is one possible cause.

What should you check?

First identify the scope of the problem.

Ask:

Does the section fail on one page or the entire store?

For example:

Homepage only
Product pages
Collection pages
One particular template
Mobile only
Desktop and mobile

Then check the section's Liquid code, settings, blocks, and any recent customizations.

If the section stopped working immediately after a code change, that change should be one of the first things you investigate.

3. Shopify CSS Bugs and Broken Mobile Layouts

Another extremely common Shopify theme problem is a layout that works perfectly on desktop but breaks on mobile.

You may see:

Text going outside the screen
Buttons becoming too wide
Images being cropped incorrectly
Sections overlapping
Broken product grids
Incorrect spacing
Horizontal scrolling
Navigation problems

This is usually related to CSS, responsive rules, theme structure, or conflicting styles.

Shopify also notes that inconsistent image aspect ratios can cause collection or product grids to display differently across screen sizes.

How to troubleshoot Shopify mobile CSS issues

Don't start adding random !important rules.

Instead:

Open the affected page.
Check it on desktop.
Test several mobile widths.
Inspect the broken element.
Find which CSS rule controls it.
Check for conflicting selectors.
Apply the smallest appropriate fix.
Test the page again.

A CSS fix that works at one screen width can still create problems at another.

That's why responsive testing is important.

Shopify mobile layout still broken?

If you've tried fixing the CSS and the layout is still not behaving correctly, I can troubleshoot Shopify CSS and responsive theme issues.

4. Shopify JavaScript Errors

Not every Shopify bug is visible in the design.

Sometimes the storefront looks completely normal, but a feature doesn't work.

For example:

Add to Cart doesn't respond
Product variants don't update
A popup doesn't open
A slider stops working
AJAX cart doesn't update
Product filters stop responding
A custom button does nothing

These problems can often be related to JavaScript.

How to find JavaScript errors

Open your browser's developer tools and check the Console.

Look for errors that appear when you perform the action that isn't working.

Then investigate:

Which JavaScript file generated the error?
Was custom JavaScript recently added?
Was an app recently installed?
Does the problem happen on every page?
Does it happen on mobile as well?

Shopify notes that storefront apps can add code directly to theme code, so app-related changes are worth investigating when a problem begins after an installation or update.

Don't simply delete JavaScript because it produces an error.

The important part is understanding why the error is happening.

5. Shopify Add to Cart Button Not Working

This is one of the more serious Shopify theme problems because the Add to Cart functionality is directly connected to the shopping experience.

A customer may select a product and click:

Add to Cart

…but nothing happens.

Possible causes include:

JavaScript errors
Variant selection problems
Broken product forms
Custom theme code
App conflicts
Cart-related JavaScript
Incorrect theme customization

How to troubleshoot an Add to Cart problem

First test more than one product.

If only one product is affected, investigate the product or variant configuration.

If every product is affected, look more closely at the theme, JavaScript, cart functionality, or apps.

Also test:

Desktop
Mobile
Incognito mode
Another browser

Shopify recommends testing the problem in different environments and checking whether it occurs on another theme.

This can help determine whether you're dealing with a theme-specific problem or something broader.

6. Shopify Theme Broken After Installing an App

Apps are one of the most useful parts of Shopify, but some apps interact directly with storefront themes.

An app may add code to the theme to provide features such as:

Reviews
Product badges
Upsells
Popups
Wishlist functionality
Product customization
Tracking
Cart features

Shopify confirms that some apps inject code directly into theme files or use theme integration mechanisms.

Sometimes a problem appears shortly after installing or updating an app.

You might notice:

Duplicate elements
Broken layouts
JavaScript errors
Missing buttons
Product page problems
Cart problems
Unexpected styling

How to check for an app conflict

Ask:

Did this problem start after an app was installed or updated?

If yes, the app should be investigated.

Shopify recommends temporarily uninstalling an app that affects the storefront as one troubleshooting method, then checking whether the problem disappears.

However, don't randomly remove important apps from a live store.

Understand what the app does and what code or functionality it has added before making changes.

7. Shopify Theme Broken After Custom Code Changes

This is probably one of the easiest ways to accidentally create a Shopify bug.

You want to make a small change.

Maybe you want to:

Change a button
Add a custom section
Modify the product page
Change the cart
Hide an element
Add custom CSS
Add JavaScript
Modify a Liquid template

The change appears simple.

But afterward, another part of the store stops working.

Shopify themes contain multiple interconnected files and can include Liquid, HTML, CSS, JavaScript and JSON. Shopify recommends duplicating a theme before making significant code edits.

Before editing Shopify theme code

Create a backup or duplicate of your theme.

Then:

Make one change at a time.
Test the storefront.
Check desktop.
Check mobile.
Test important functionality.
Only then move to the next change.

This makes troubleshooting much easier if something breaks.

How to Find the Real Cause of a Shopify Bug

One of the biggest mistakes people make is trying random fixes.

For example:

"The button doesn't work, so I'll change the button CSS."

But the actual problem could be JavaScript.

Or:

"The section disappeared, so I'll add it again."

But the real problem could be a Liquid error.

A better debugging process is:

1. Reproduce the problem

Open the store and reproduce the exact issue.

2. Identify the affected area

Is it:

Homepage?
Product page?
Collection?
Cart?
Mobile?
Desktop?

3. Check recent changes

Look at:

Theme edits
Custom Liquid
CSS
JavaScript
App installations
Theme updates

4. Inspect errors

Check browser console errors and Shopify theme warnings.

5. Identify the source

Determine whether the problem comes from:

Liquid → CSS → JavaScript → Theme → App → Configuration

6. Fix the actual cause

Avoid changing unrelated code.

7. Test everything

Test the original problem again after the fix.

Shopify Theme Troubleshooting Checklist

Before making a major change, check these things:

Theme

Is the problem limited to one theme?
Was the theme recently updated?
Was custom code recently added?

Liquid

Is there a syntax error?
Is a snippet broken?
Is a variable missing?

CSS

Does the problem happen only on mobile?
Is another selector overriding the style?
Are elements overflowing?

JavaScript

Are there console errors?
Does the feature work after disabling a script?
Was custom JavaScript recently added?

Apps

Was an app recently installed?
Was an app updated?
Does the problem disappear when the app is removed?

Testing

Desktop
Mobile
Different browser
Incognito mode
Another theme

Shopify's own troubleshooting process follows many of these same isolation steps: test the environment, compare themes, and investigate recently installed or updated apps.

When Should You Hire a Shopify Developer?

Not every Shopify issue requires a developer.

Simple content or theme-editor changes may be easy to handle yourself.

But professional troubleshooting becomes useful when you're dealing with:

Shopify Liquid errors
Broken theme sections
CSS conflicts
Responsive problems
JavaScript errors
Add to Cart issues
Product page bugs
Cart problems
Custom code errors
App/theme conflicts
Complex theme customizations

Shopify also states that its support has limitations around significant custom theme code and third-party code, which can make developer assistance useful for heavily customized stores.

Need Help Fixing a Shopify Theme Bug?

If you've tried troubleshooting your Shopify store and the problem is still there, I can help investigate the issue and identify whether it's related to Liquid, CSS, JavaScript, theme code, responsive layout, sections, cart functionality, or custom code.

👉 Fix a Shopify Bug / Theme Issue on Fiverr

You can send the exact issue, affected page, screenshot, or error message so the problem can be reviewed before choosing the appropriate service.

Final Thoughts

Shopify theme bugs can look complicated, but many of them become easier to solve once you identify where the problem actually originates.

A Liquid error requires a different approach than a CSS problem.

A mobile layout issue is different from a JavaScript error.

And an app conflict should be investigated differently from a broken custom section.

The key is to avoid random changes and follow a structured process:

Reproduce → Inspect → Identify → Fix → Test

If you have a Shopify store with a theme bug that you can't resolve, you can get Shopify bug-fixing help on Fiverr.