Fix “Cannot access offset of type string on string” in WPForms (Name field)

Short answer: this error means WPForms tried to treat your Name field value like an array, but PHP says it is just a string. So something in your form setup or custom code is changing the data shape.

Let us walk through how to make the site stable, then track down which thing is doing that.

Where to start

• If your whole site is white-screening
• If you just want to understand the error
• If this started after a PHP or plugin update
• If it only happens on one specific form
• If you use custom WPForms PHP snippets
• If it began after adding another plugin or theme

Step 0: Get your site back online

If this fatal error is taking down the whole site, stabilize things first.

1. Connect over FTP or your hosting file manager.
2. Go to wp-content/plugins/.
3. Rename the wpforms-lite folder to something like wpforms-lite-disabled.

WordPress will stop loading WPForms, and the site should come back.

Once we have identified and fixed the cause, you can rename the folder back to wpforms-lite and reactivate the plugin in the dashboard.

What this error actually means

The key part of the message is:

TypeError: Cannot access offset of type string on string

This is PHP saying:

“You tried to do $something['first'] but $something is a text string, not an array.”

Inside WPForms, the Name field expects an array like:

$field_submit = [
    'first'  => 'John',
    'last'   => 'Doe',
    'middle' => '',
];

If something turns that into a plain string such as "John Doe", the Name field code in class-name.php still tries to do $field_submit['first']. On PHP 8 and up, that turns from a warning into a fatal error.

Step 1: Update WPForms and check PHP version

First, make sure you are not fighting a bug that was already fixed.

1. Log in to the WordPress admin.
2. Go to Dashboard → Updates.
3. Update WPForms Lite to the latest version.
4. Update WordPress core and other plugins so everything is current.

Then check your PHP version in Tools → Site Health → Info → Server.

• WPForms supports modern PHP versions. Running an old PHP (for example 7.3 or below) makes type issues more likely.
• If your host lets you pick PHP, aim for something in the supported range (your host or WPForms docs will list this).

Retry the form or the page that previously crashed.

• If the error is gone, it was likely an old WPForms version that did not play well with your PHP version.
• If it is still there, continue below.

Step 2: Check which form and which Name field is broken

You want to know if this is global or limited to one form.

Find the failing form

1. Turn on logging in wp-config.php (if not already):

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );

2. Trigger the error again by loading the page or submitting the form.
3. Open wp-content/debug.log and look for the line with class-name.php.

Often the log will also show the form ID or field ID near the stack trace. Even if it does not, you now know that the crash happens on a specific page.

Rebuild the Name field

There are cases in the WPForms support forums where notices and warnings from class-name.php went away just by recreating a field, which suggests the stored field settings can get into a bad shape.

On the affected form:

1. Go to WPForms → All Forms and edit the form that triggers the error.
2. Delete the existing Name field.
3. Drag a fresh Name field from the left panel.
4. Set its format to match what you want:
   • Simple
   • First Last
   • First Middle Last
5. Save the form and test again on the front end.

If the fatal error disappears after rebuilding the Name field, the problem was likely a corrupt or outdated field configuration. You can stop here and keep an eye on your logs.

If the error persists, move on.

Step 3: Look for custom code that touches WPForms

WPForms has a lot of developer hooks. It is common to see custom snippets that read or change the Name field, for example to block certain names or tweak validation.

Those snippets sometimes assume the data is always an array and do not check the type. On PHP 8 that can blow up with the same error you are seeing.

Search for WPForms hooks

In your theme or code snippets plugin:

• Open functions.php and any “code snippet” plugins you use.
• Search for wpforms_ and especially:
  • wpforms_process_validate_name
  • wpforms_process_validate_ (any field type)
  • wpforms_process
  • wpforms_field_properties_name

If you find a function that works with the Name field, check how it handles the submitted value.

Make sure custom validation checks the data type

Anything like this is fine:

function mysite_name_validation( $field_id, $field_submit, $form_data ) {

    // Make sure the value is the expected array shape
    if ( ! is_array( $field_submit ) ) {
        return;
    }

    // Safe to access subfields now
    $first = isset( $field_submit['first'] ) ? $field_submit['first'] : '';
    $last  = isset( $field_submit['last'] ) ? $field_submit['last'] : '';

    // Your custom logic here
}
add_action( 'wpforms_process_validate_name', 'mysite_name_validation', 10, 3 );

But if you see code that does this with no type check:

$submitted_name = $field_submit['first'] . ' ' . $field_submit['last'];

and there is any chance $field_submit might be a string, PHP 8 will throw “Cannot access offset of type string on string”.

Temporarily comment out that snippet or wrap it in an is_array() check as shown above. Then test the form again.

• If the error is gone, the custom snippet was the cause.
• You can keep the snippet but always guard it with is_array() and isset().

Step 4: Run a quick plugin and theme conflict test

If you do not have custom code or the checks above look fine, the next most likely cause is another plugin or theme filtering $_POST or form data in a way that flattens the Name field into a string.

Safe conflict test

1. On a staging site if possible. Otherwise pick a low traffic time.
2. Deactivate all plugins except:
   • WPForms Lite
3. Switch to a default theme like Twenty Twenty-Five.
4. Test the same form page again.

• If the error disappears: one of the deactivated plugins or your old theme is interfering.
• If the error remains even with only WPForms and a default theme: this points more toward data corruption or a deeper WPForms bug on your setup.

Find the exact offender

If the error disappeared during the conflict test:

1. Reactivate plugins one at a time.
2. After each activation, test the form again.
3. When the error returns, the last plugin you activated is the conflict source.

Once you identify that plugin or the theme:

• Check its settings for anything that touches forms, HTML filtering, or $_POST data.
• Look for options like “sanitize all requests” or “stringify arrays” and try turning those off for the form page.
• If needed, contact that plugin’s author with the stack trace that mentions class-name.php.

Step 5: When to contact WPForms support or your host

At this point you have:

• Updated WPForms and WordPress.
• Rebuilt the Name field on the affected form.
• Checked or disabled any custom WPForms snippets.
• Run a plugin and theme conflict test.

If none of that stops the fatal error, this is likely something very specific to your installation.

What to send WPForms support

Open a ticket with WPForms (or post in their WordPress.org forum if you are on Lite) and include:

• The full error line that mentions Cannot access offset of type string on string and class-name.php.
• Your WordPress, WPForms, PHP, and theme versions.
• Whether the error happens on all forms or only one.
• Whether it goes away with only WPForms active and a default theme.

This gives them enough information to reproduce or point out a known edge case.

Verification checklist

You are in good shape when:

• The form page loads without a fatal error.
• Submissions that use the Name field work correctly.
• Your debug.log no longer shows new entries from includes/fields/class-name.php.
• Any custom Name validation snippets are guarded with is_array() checks.

Still stuck?

For AI help

Scroll down and click Continue Chat. Tell me:

1. The exact error line from your log.
2. Your PHP version and WPForms Lite version.
3. Whether it affects one form or all forms.
4. Any custom WPForms snippets you are using.

I can help you walk through the log and narrow it down further.

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