Unable to load dynamic library 'C:\xampp\php\ext\php_oci8.dll' - %1 is not a valid Win32 application

Your error shows a built-type mismatch.

Resolve it by following these steps:

Make sure you download and install oracle instantclient at: http://www.oracle.com/technetwork/topics/winsoft-085727.html, but note:

1. Take note of your Oracle database version; use Version 12.1.x for Oracle database 12c and Version 11.1.x for 11g releases.
2. In either case, make sure you download the Basic Lite version of the Oracle instantclient.

After that, do add location of your Oracle instantclient to your System variable Path under your Environment Variables. Do equally ensure that you have both the PHP of your xampp and its ext available and set there as well (if not, do add them).

Then, proceed to add a new System variable with TNS_ADMIN as variable name and the location to Oracle instantclient as variable value.

Also, define your User variables PATH with the same the location to Oracle instantclient as value.

After this stage, restart your computer for a full propagation of the newly defined environment variables.

Once on, you may open your Windows Command Prompt and run where oci* to ensure that you had your environment variables well defined; the response should look like this:

C:\Users\flex>where oci*C:\oraclexe\app\oracle\product\11.2.0\server\bin\oci.dllC:\oraclexe\app\oracle\product\11.2.0\server\bin\ocijdbc11.dllC:\oraclexe\app\oracle\product\11.2.0\server\bin\ocijdbc11.symC:\oraclexe\app\oracle\product\11.2.0\server\bin\ociw32.dllC:\instantclient_11_2\oci.dllC:\instantclient_11_2\oci.symC:\instantclient_11_2\ocijdbc11.dllC:\instantclient_11_2\ocijdbc11.symC:\instantclient_11_2\ociw32.dllC:\instantclient_11_2\ociw32.sym

If not, your must have missed something and need to revisit the process, ensuring to completing it effectively.

You may now proceed to your php.ini file (provided environment variables are well defined) and enable your oci extensions (php_oci8.dll and php_oci8_11g.dll) by uncommenting them; you can achieve that by simply removing the semi column (;) before the said extensions.

Do remember to save your php.ini file, then, restart or start your apache if it isn't already running.

To check your PHP oci8 configurations are enabled, you may go back to your Windows Command Prompt and run: php --ri oci8; the response should be similar to the one below:

C:\Users\flex>php --ri oci8OCI8 Support => enabledOCI8 DTrace Support => disabledOCI8 Version => 2.1.1Revision => $Id: 86f22a208f89dcd5b305e82929a7429683968b11 $Oracle Run-time Client Library Version => 11.2.0.4.0Oracle Compile-time Instant Client Version => 10.2Directive => Local Value => Master Valueoci8.max_persistent => -1 => -1oci8.persistent_timeout => -1 => -1oci8.ping_interval => 60 => 60oci8.privileged_connect => Off => Offoci8.statement_cache_size => 20 => 20oci8.default_prefetch => 100 => 100oci8.old_oci_close_semantics => Off => Offoci8.events => Off => OffStatistics =>Active Persistent Connections => 0Active Connections => 0

Alternatively, you can create a PHP file with <?php phpinfo(); ?> as content, then open it in your browser and search for oci8 occurrences; it should show enabled there as well.

It seems that you downloaded the DLL for a different architecture and pointed to it in your php.ini, instead of using the bundled DLL and simply un-commenting the default entry in php.ini.

I just downloaded the same version, XAMPP 3.2.2 x86, with PHP 7.1, and it ships with the DLL file that you need, which is installed to C:\xampp\php\ext\php_oci8_12c.dll.

You appear to have done everything else correctly.

To fix the issue, ensure that the effective php.ini (by default, C:\xampp\php\php.ini) references only the default file (remove the erroneous entry you added for php_oci8.dll), like so:

extension=php_oci8_12c.dll  ; Use with Oracle Database 12c Instant Client

Restart Apache and the problem should be resolved.