Fix Blogger post permalinks after import into WordPress

blogger2wordpresslinkfix.php

<?php
/**
 * Rewrite WordPress URLs to match Blogger permalinks exactly.
 *
 * This script is intended for one time use only after importing Blogger
 * content into WordPress and should be removed from the server immediately
 * after the script has run one time. It shouldn't be needed again after the
 * initial rewrite.
 *
 * @version 0.1.0
 * @author  WP Site Care
 * @link    http://www.wpsitecare.com/import-blogger-to-wordpress/
 */

require_once 'wp-load.php';

/**
 * Get all posts with blogger permalinks.
 *
 * @since  0.1.0
 * @access public
 * @global $wpdb
 * @return array|bool $posts an array of WP_Post objects withe blogger permalinks
 */
function sitecare_get_blogger_posts() {
    global $wpdb;

    $posts = (array) $wpdb->get_results(
        "SELECT post_id, meta_value FROM $wpdb->postmeta WHERE meta_key = 'blogger_permalink'"
    );

    return empty( $posts ) ? false : $posts;
}

/**
 * Update posts to match their previous blogger permalink structure.
 *
 * @since  0.1.0
 * @access public
 * @global $wpdb
 * @return bool true if posts have been updated
 */
function sitecare_fix_blogger_permalinks() {
    global $wpdb;
    $wpdb->show_errors = true;

    $updated = false;
    $delete = '<h1>Please delete this file immediately.</h1>';

    if ( ! $posts = sitecare_get_blogger_posts() ) {
        echo '<h2>There are no posts to update.</h2>';
        echo $delete;
        return $updated;
    }

    foreach ( $posts as $post ) {
        if ( ! is_object( $post ) ) {
            continue;
        }

        $slug = isset( $post->meta_value ) ? explode( '/', $post->meta_value ) : false;

        if ( ! $slug || ! isset( $slug[3], $post->post_id ) ) {
            continue;
        }

        $slug = explode( '.', $slug[3] );

        if ( ! isset( $slug[0] ) ) {
            continue;
        }

        $wpdb->query( $wpdb->prepare(
            "UPDATE $wpdb->posts SET post_name = %s WHERE ID = %s", $slug[0], $post->post_id
        ) );

        if ( $wpdb->last_error ) {
            echo $wpdb->last_error;
        } else {
            $updated = true;
            $title = get_the_title( $post->post_id );
            echo "<p>The permalink for <i>{$title}</i> has been updated to <code>{$slug[0]}</code></p>";
        }
    }

    if ( $updated ) {
        echo '<h2>Your permalinks have been fixed.</h2>';
        echo $delete;
    }

    return $updated;
}

sitecare_fix_blogger_permalinks();

Guide: https://www.wpsitecare.com/import-blogger-to-wordpress/