解决PHP7.3下Magento1.9.4管理后台显示空白页面的问题

Magento 1.9.4版本的官方发布说明上，是支持到PHP7.2版本的。大伟哥换了新的阿里云服务器以后，安装的是PHP7.3，当时也有些担心会不会不兼容，但是迁移过来以后，发现各个页面都能正常打开，也就放着不管了。

直到今天，想进Magento后台去修改某项配置，却发现输入管理员用户名和密码之后，页面跳转不正常，打开的页面是空白页，不能正常显示后台内容。这吓了我一跳，难不成真是PHP版本不兼容的问题？

Apache的错误日志显示如下：

sudo tail /var/log/apache2/error.log

Got error 'PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function curl_setopt_array() in /var/www/html/xxxxxx.cn/lib/Varien/Http/Adapter/Curl.php:78\nStack trace:\n#0 /var/www/html/xxxxxx.cn/lib/Varien/Http/Adapter/Curl.php(177): Varien_Http_Adapter_Curl->_applyConfig()\n#1 /var/www/html/xxxxxx.cn/app/code/core/Mage/AdminNotification/Model/Feed.php(163): Varien_Http_Adapter_Curl->write('GET', 'http://notifica...', '1.0')\n#2 /var/www/html/xxxxxx.cn/app/code/core/Mage/AdminNotification/Model/Feed.php(83): Mage_AdminNotification_Model_Feed->getFeedData()\n#3 /var/www/html/xxxxxx.cn/app/code/core/Mage/AdminNotification/Model/Observer.php(50): Mage_AdminNotification_Model_Feed->checkUpdate()\n#4 /var/www/html/xxxxxx.cn/app/code/core/Mage/Core/Model/App.php(1374): Mage_AdminNotification_Model_Observer->preDispatch(Object(Varien_Event_Observer))\n#5 /var/www/html/xxxxxx.cn/app/code/core/Mage/Core/Model/App.php(1353): Mage_Core_Model_App->_callObserverMethod(Object(Mage_AdminNotific...'

这不会是curl的锅吧？试着安装一下对应版本的curl：

sudo apt install php7.3-curl
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  php7.3-curl
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 30.7 kB of archives.
After this operation, 135 kB of additional disk space will be used.
Get:1 http://mirrors.cloud.aliyuncs.com/debian-security buster/updates/main amd64 php7.3-curl amd64 7.3.14-1~deb10u1 [30.7 kB]
Fetched 30.7 kB in 0s (110 kB/s)      
Selecting previously unselected package php7.3-curl.
(Reading database ... 41545 files and directories currently installed.)
Preparing to unpack .../php7.3-curl_7.3.14-1~deb10u1_amd64.deb ...
Unpacking php7.3-curl (7.3.14-1~deb10u1) ...
Setting up php7.3-curl (7.3.14-1~deb10u1) ...

Creating config file /etc/php/7.3/mods-available/curl.ini with new version
Processing triggers for libapache2-mod-php7.3 (7.3.14-1~deb10u1) ...
Processing triggers for php7.3-fpm (7.3.14-1~deb10u1) ...
NOTICE: Not enabling PHP 7.3 FPM by default.
NOTICE: To enable PHP 7.3 FPM in Apache2 do:
NOTICE: a2enmod proxy_fcgi setenvif
NOTICE: a2enconf php7.3-fpm
NOTICE: You are seeing this message because you have apache2 package installed.

我晕，果然是换新服务器后忘记安装并启用php7.3-curl了。现在刷新页面，后台能正常打开了。

至于Magento 1.9.4和php7.3其他不兼容的地方，目前还没有发现。