如何修复CentOS 6.5中yum安装php-mysqli及安装后的报错问题

Hey there, let’s work through these two php-mysqli headaches you’re facing on CentOS 6.5— I’ve debugged similar problems plenty of times, so let’s break it down step by step.

Problem 1: Errors when installing php-mysqli via YUM #

CentOS 6 is past its end-of-life, so most default repos are no longer active, which is the #1 cause of YUM install failures here. Let’s cover the most common fixes:

• Fix outdated YUM repos
  Since official CentOS 6 repos are offline, you’ll need to switch to archived repos. Here’s how:

  1. Back up your existing repo config:

     mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
     

  2. Create a new CentOS-Base.repo file with archived sources. Open it in an editor:

     vi /etc/yum.repos.d/CentOS-Base.repo
     

     Paste this content (uses an archived CentOS 6 repo):

     [base]
     name=CentOS-6 - Base - Archived
     failovermethod=priority
     baseurl=http://mirrors.aliyun.com/centos-vault/6.10/os/$basearch/
     gpgcheck=1
     gpgkey=http://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-6

     [updates]
     name=CentOS-6 - Updates - Archived
     failovermethod=priority
     baseurl=http://mirrors.aliyun.com/centos-vault/6.10/updates/$basearch/
     gpgcheck=1
     gpgkey=http://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-6

     [extras]
     name=CentOS-6 - Extras - Archived
     failovermethod=priority
     baseurl=http://mirrors.aliyun.com/centos-vault/6.10/extras/$basearch/
     gpgcheck=1
     gpgkey=http://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-6

  3. Clean and refresh YUM cache:

     yum clean all && yum makecache
     

  Now try installing php-mysqli again with yum install php-mysqli.

• Fix PHP version mismatches
  CentOS 6 ships with PHP 5.3 by default, but if you’ve installed a newer PHP version (like 5.4/5.5 from third-party repos), the package name might differ. First check your PHP version:

  php -v
  

  Then install the matching mysqli package— for example, if you’re on PHP 5.4, use yum install php54-mysqli.

• Fix dependency conflicts
  If YUM throws dependency errors, try skipping broken packages temporarily (only do this if you’re sure the broken dependencies aren’t critical):

  yum install --skip-broken php-mysqli
  

  Or resolve the missing dependencies first by installing the required packages manually.

Problem 2: Abnormal behavior even after installing php-mysqli #

Installing the package doesn’t always mean the extension is working correctly. Let’s troubleshoot the most common culprits:

• Check if mysqli is enabled in PHP
  First verify if the extension is loaded:

  php -m | grep mysqli
  

  If there’s no output, it’s not enabled. Here’s how to fix that:

  1. Find your active php.ini file:

     php --ini | grep "Loaded Configuration File"
     

  2. Open the file in an editor and add/uncomment this line:

     extension=mysqli.so
     

  3. Restart your web service to apply changes:
     • For Apache: service httpd restart
     • For PHP-FPM (if using Nginx): service php-fpm restart

• Verify extension path is correct
  Sometimes PHP can’t find the mysqli.so file. Check your extension directory:

  php -i | grep "extension_dir"
  

  Make sure mysqli.so exists in that path (e.g., /usr/lib64/php/modules/ for 64-bit systems). If not, you may need to specify the full path in php.ini:

  extension_dir = "/usr/lib64/php/modules/"
  extension=mysqli.so
  

• Fix file permission issues
  Ensure the mysqli.so file has proper permissions for your web server to read it:

  chmod 644 /usr/lib64/php/modules/mysqli.so
  

  Also confirm the web server user (usually apache or nginx) has read access to the file and its parent directories.

• Check MySQL-PHP compatibility
  CentOS 6’s default MySQL version is 5.1. If you’ve upgraded to MySQL 5.6+/MariaDB, there might be compatibility gaps with the system’s php-mysqli package. In this case, you can either:

  • Downgrade MySQL to 5.1 to match the system PHP
  • Recompile the mysqli extension against your newer MySQL version (more advanced)

• Debug code-level issues
  Sometimes the problem isn’t with the extension itself, but your code. Test with a simple connection script to rule this out:

  <?php
  // Replace with your database credentials
  $host = 'localhost';
  $user = 'your_username';
  $pass = 'your_password';
  $dbname = 'your_database';
  
  $conn = mysqli_connect($host, $user, $pass, $dbname);
  if (!$conn) {
      die('Connection failed: ' . mysqli_connect_error());
  }
  echo 'Successfully connected to the database!';
  mysqli_close($conn);
  ?>
  

  Save this as test_mysqli.php in your web root, access it via browser, and check the exact error message— this will point you to whether it’s a connection issue or something else.

内容的提问来源于stack exchange，提问作者mynk