How to install cURL library for PHP on Windows?

Question

I'm starting with this error:

Call to undefined function curl_init()

Fine, so I go to PHP's php.ini file and uncomment:

;extension=curl to extension=curl

I restart Apache, and?

Call to undefined function curl_init()

I added the full PHP directory to the system paths, and?

Call to undefined function curl_init()

So I check phpinfo() and I see the module is loaded for cURL but no other string instances mentioned:

PHP's get_loaded_extensions() does not list cURL.

So I figure, I might as well install a fresh version of cURL.

So the main cURL page doesn't have binaries for Windows of course. So I eventually find my way to https://curl.se/download.html#Win64. Now I've gone through their documentation and they don't have anything about installing the binaries but they have information about building them. Which is like having a guy give you a spare inflated tire but not the tools to install it but he wants to tell you where to get the spare next time, not helpful.

So I've got a ZIP file with cURL and the readme file has no installation instructions. None of the documentation from what I can see clarifies what to do with the files.

1. Do I simply drag-and-drop the files to the php\ext folder? It contains a libcurl-x64.dll file, I guess I can either rename it to simply libcurl.dll or add a custom extension entry in php.ini but I'm not sure and I can't find documentation specific to that.
2. Do I have to add a custom entry for my php.ini file?

How do I install (the binary version of) cURL for PHP on Windows?

• Running PHP 8.3 on Windows 10 x64.
• php.ini path is set: extension_dir = "C:\PHP\ext\".
• PHP cURL's author's name appears in phpinfo() however not the cURL header like on my live LAMP server.
• Running php.exe from the command line does not return error messages.

Edit 1

I checked the Apache error log and found this:

PHP Warning: PHP Startup: Unable to load dynamic library 'curl' (tried: C:\PHP\ext\curl (The specified module could not be found), C:\PHP\ext\php_curl.dll (The specified module could not be found)) in Unknown on line 0

I have the extension absolutely defined (extension=C:\PHP\ext\php_curl.dll) and still got this error.

Edit 2

I came across a tutorial to run the following from the command line:

deplister.exe ext\php_curl.dll

It produced the following list:

• php8ts.dll,OK
• libcrypto-3-x64.dll,OK
• libssl-3-x64.dll,OK
• CRYPT32.dll,OK
• WLDAP32.dll,OK
• Normaliz.dll,OK
• libssh2.dll,OK
• nghttp2.dll,OK
• KERNEL32.dll,OK
• ADVAPI32.dll,OK
• WS2_32.dll,OK
• bcrypt.dll,OK
• VCRUNTIME140.dll,OK
• api-ms-win-crt-heap-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-stdio-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-string-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-runtime-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-convert-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-filesystem-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-utility-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-time-l1-1-0.dll,NOTFOUND
• api-ms-win-crt-math-l1-1-0.dll,NOTFOUND

So clearly some version of Visual C++ is missing. I'll post another follow-up soon.

Answer 1

You need to ensure the ext directory is set correctly In your php.ini, check this line: extension_dir = "ext" It should point to the ext folder inside your PHP installation (where php_curl.dll is located). Example: extension_dir = "C:\xampp\php\ext" then restart your web server

• If you’re using XAMPP, restart Apache from the XAMPP control panel.
• If you’re using IIS or another setup, restart that service. Verify installation Run:

php -m | findstr curl

Or create a phpinfo() page in your web root:

<?php phpinfo(); ?> 

Then open it in your browser and check for curl.

Answer 2

Problem: Unable to load dynamic library 'curl' / 'php_curl.dll' could not be found

Likely Cause: Wrong extension_dir value, missing DLL, wrong build (architecture), or dependent DLLs missing Solution: Check path, copy the correct DLL, ensure all required dependent DLLs are present, match architecture / thread safety.

Answer 3

Someone elsewhere on the web said that dumping the libssh2.dll file in to Apache\bin directory fixed the problem. I found more documentation and these basic instructions fixed cURL to work on Windows:

Edit the C:/Apache/conf/httpd.conf file:

• LoadFile "C:/Apache/bin/libeay32.dll"
• LoadFile "C:/Apache/bin/libssh2.dll"
• LoadFile "C:/Apache/bin/ssleay32.dll"

Restart Apache and cURL will work correctly. I think this has something to do with OpenSSL offhand but 99.9% of everything PHP+cURL related is simply removing the semi-colon and restarting Apache. I think people forget that, hello, it's going to make Internet requests with the https:// protocol and it needs a way to do so securely.