My excuses, I hadn't found the correct log file. I'm getting:

PHP Warning:  PHP Startup: Unable to load dynamic library 'curl' (tried: ext\\curl (No se puede encontrar el m\xef\xbf\xbddulo especificado.), ext\\php_curl.dll (No se encontr\xef\xbf\xbd el proceso especificado.)) in Unknown on line 0

Likely the dependent DLLs (such as libssh2.dll) can't be found.
Did you add the PHP folder to your PATH[1]?

[1] <https://www.php.net/manual/en/curl.installation.php>

Yes, I have. I'm actually using a symlink (mklink command) so the path never changes, I hope that's not an issue.

According to Process Monitor, "httpd.exe" is trying to load "libssh2.dll" from all sort of locations except PHP directory:

- Apache's base and "bin" directory
- C:\Windows\System32\libssh2.dll
- C:\Windows\System\libssh2.dll
- C:\Windows\libssh2.dll
- Graphics Magick directory
- Oracle Instant Client directory
- C:\Srv\PHP\PEAR\libssh2.dll

... so it's obviously not taking PHP folder into consideration. It's weird because this same set-up works fine for 7.0, 7.1 and 7.2. I'll check everything again *sigh*

Also check that there's no "wrong" DLL loaded.

Apache (actually Windows) won't try to load libssh2 from the PHP directory because that's not where it knows to look: it checks the location of the executable, system directories, and the system or user PATH depending how the application is being run. And I don't know if a symlink will work, assuming it's in one of those locations of course.

Put libssh2 in the Apache directory, in System32, or add PHP to the system PATH and restart.

Any news here?

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Sorry for the delay (a trip got in between). I've verified to the best of my ability that:

- PHP directory belongs to PATH
- Apache recognises such PATH
- Apache finds and loads successfully the copy of libssh2.dll provided by PHP binaries (according to Process Monitor)

... yet Curl is still unavailable under Apache (though it loads fine in command-line):

PHP Warning:  PHP Startup: Unable to load dynamic library 'curl' (tried: ext\\curl (No se puede encontrar el m\xef\xbf\xbddulo especificado.), ext\\php_curl.dll (No se encontr\xef\xbf\xbd el proceso especificado.)) in Unknown on line 0

I've also tried almost every 7.3.x release for Win64 and learnt that:

- 7.3.0 and 7.3.2 work fine.
- 7.3.3 to 7.3.6 fail.

I mentioned I'm using symlinks—I've switched to regular directories just to be safe. I've restarted several times. Nothing changed.

I'm totally clueless so far. Is there anything else you'd like me to try?

Thanks for the feedback!

Have you tried to use an absolute path for extension_dir?

With an absolute path:

PHP Warning:  PHP Startup: Unable to load dynamic library 'curl' (tried: C:\\Opt\\PHP\\ext\\curl (No se puede encontrar el m\xef\xbf\xbddulo especificado.), C:\\Opt\\PHP\\ext\\php_curl.dll (No se encontr\xef\xbf\xbd el proceso especificado.)) in Unknown on line 0

You can run the following script from Apache:

  <?php
  exec('"C:\\Opt\\PHP\\deplister" "C:\\Opt\\PHP\\ext\\php_curl.dll"', $output);
  print_r($output);

All DLLs should be OK.

Array
(
    [0] => php7ts.dll,OK
    [1] => libcrypto-1_1-x64.dll,OK
    [2] => libssl-1_1-x64.dll,OK
    [3] => WLDAP32.dll,OK
    [4] => Normaliz.dll,OK
    [5] => libssh2.dll,OK
    [6] => nghttp2.dll,OK
    [7] => KERNEL32.dll,OK
    [8] => WS2_32.dll,OK
    [9] => VCRUNTIME140.dll,OK
    [10] => api-ms-win-crt-stdio-l1-1-0.dll,OK
    [11] => api-ms-win-crt-string-l1-1-0.dll,OK
    [12] => api-ms-win-crt-heap-l1-1-0.dll,OK
    [13] => api-ms-win-crt-convert-l1-1-0.dll,OK
    [14] => api-ms-win-crt-runtime-l1-1-0.dll,OK
    [15] => api-ms-win-crt-time-l1-1-0.dll,OK
    [16] => api-ms-win-crt-utility-l1-1-0.dll,OK
    [17] => api-ms-win-crt-filesystem-l1-1-0.dll,OK
    [18] => api-ms-win-crt-environment-l1-1-0.dll,OK
)

Since I cannot reproduce this, and there don't seem to be (many)
others having the same issue, I still guess there's a setup
problem somewhere, but I have no ideas how to debug that further.

Fair enough. I've just got a similar computer to test and it runs flawlessly here. I bet it's an antivirus issue or something like that. I'll dig deeper in to it.

I've upgraded Apache from httpd-2.4.29-Win64-VC15 to httpd-2.4.39-win64-VS16 (Apache Lounge builds) and that immediately solved my issues.

I am having this same exactly problem using VC16 version of Apache (downloaded from apache lounge) and 7.4 version of PHP. Tried adding many directories to PATH, tried copying some dlls around windows, and nothing solved the problem.

I am running windows 10 with latest updates. I am having exactly the same problem the other person reported here but supposedly that person said installing Apache with another VCx solved - to my case it didnt!