php_pdo_pgsql.dll errors may appear as:
PHP Warning: PHP Startup: Unable to load dynamic library 'pdo_pgsql'
The specified module could not be found.
You may also see:
The specified procedure could not be found
The operating system cannot run %1
PDOException: could not find driver
The 60-second answer
php_pdo_pgsql.dll is PHP’s PDO driver for PostgreSQL. It is not a Windows component, DirectX file, game DLL, or ordinary hardware-driver file.
The safest fix is to repair or reinstall the exact PHP package that supplied it, then enable pdo_pgsql in the PHP configuration used by the failing application. Do not download the DLL from a random DLL website, copy it into C:WindowsSystem32, or register it with regsvr32.
The file normally belongs in the PHP installation’s ext folder, for example:
C:phpextphp_pdo_pgsql.dll
The exact folder depends on whether PHP came from the official ZIP package, XAMPP, WAMP, Laragon, IIS, Apache, or an application that embeds PHP.
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What the file does
php_pdo_pgsql.dll implements PDO access to PostgreSQL. An application using PHP’s PDO interface needs this driver to connect to PostgreSQL databases.
pdo_pgsql and pgsql are separate extensions:
pdo_pgsqlis used by applications built on PHP Data Objects.pgsqlsupplies the proceduralpg_*API.- An application using PDO does not become fixed merely because
pgsqlis enabled.
PDO itself must also be available. The PostgreSQL driver is loaded after PDO when PDO is separately built.
Installing a PostgreSQL server locally is not always necessary. The PHP extension needs PostgreSQL’s client library, particularly libpq.dll, but the database server may be on another computer or hosted elsewhere.
Why Windows says the module is missing when the file exists
Windows uses “module could not be found” for two different situations:
php_pdo_pgsql.dllis genuinely absent.- The file exists, but Windows cannot load one of its dependencies.
The dependency may be libpq.dll, the Microsoft Visual C++ runtime, or another library required by the matching PHP build. A wrong PHP version, architecture, thread-safety mode, or compiler build can produce similar errors.
The PHP process matters too. Command-line PHP, Apache, and IIS may use different:
- PHP installations
php.inifilesextension_dirsettings- environment variables
- service-account
PATHvalues
That is why php -m can work at a command prompt while a website still reports could not find driver.
Step 1: Identify the PHP installation that is failing
Open Command Prompt and run:
where php
php --ini
php -v
php -i | findstr /i "Architecture Thread Safety extension_dir Loaded"
php -m | findstr /i "PDO pdo_pgsql pgsql"
Check the results carefully.
where php can show multiple PHP installations. php --ini identifies the configuration used by the command line. The php -i command shows the architecture, thread-safety status, extension directory, and loaded configuration.
If this is a website, create a temporary PHP diagnostic page in the site’s document root:
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<?php phpinfo();
Open that page through the affected website and check:
- Loaded Configuration File
- extension_dir
- Architecture
- Thread Safety
- Whether a
pdo_pgsqlsection appears
Delete the diagnostic page after checking it because it exposes configuration details.
Step 2: Check whether the file is actually present
Open the extension_dir shown by PHP. In File Explorer:
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extension_dirpath. - Press Windows key + E.
- Paste the path into the address bar.
- Look for
php_pdo_pgsql.dll.
If it is present, do not replace it immediately. The error may be caused by libpq.dll, the Visual C++ runtime, or a build mismatch.
If it is absent, the PHP installation is incomplete, damaged, or the wrong folder is configured. Continue with the package repair in Step 4 rather than downloading an isolated DLL.
Step 3: Confirm the PHP build matches the extension
PHP for Windows is distributed in different combinations, including:
- 32-bit or 64-bit
- Thread Safe, usually used with Apache module setups
- Non Thread Safe, commonly used with IIS/FastCGI and command-line PHP
- Different PHP versions and compiler builds
A 64-bit Windows installation can run 32-bit PHP. The DLL must match PHP, not merely the operating system.
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Do not copy a DLL from another PHP folder just because the filename matches. Mixing files can create a different version conflict.
For Apache, check whether the installation expects Thread Safe PHP. For IIS or FastCGI, check whether it expects Non Thread Safe PHP. If you are unsure, replace the complete PHP package with the matching distribution instead of mixing individual files.
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Step 4: Repair or reinstall the owning PHP package
This is the most reliable fix when php_pdo_pgsql.dll is missing or the PHP folder is damaged.
For a standalone PHP ZIP installation
- Identify the PHP version and architecture from
php -v. - Obtain the matching official PHP for Windows ZIP package.
- Extract it to a new folder rather than overwriting the old folder immediately.
- Copy your required configuration settings into the new
php.ini. - Confirm that the new
extfolder containsphp_pdo_pgsql.dll. - Set the web server or application to use the new PHP directory.
- Check that
extension_dirpoints to the newextfolder. - Restart Apache, IIS, or the relevant PHP service.
Use the same PHP version family, x86 or x64 architecture, and TS or NTS mode required by the application. Replacing the entire matching package is safer than copying only php_pdo_pgsql.dll.
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For XAMPP, WAMP, Laragon, or a packaged application
Use the product’s repair, update, or reinstall process.
Before changing anything, back up:
- Website files
- Application configuration
- Databases and database credentials
- The current
php.ini
If the problem began after an application update, use its repair option or reinstall the same application version from its official installer. For a packaged game or program, use its launcher’s Verify, Repair, or equivalent file-checking feature if available.
The package that installed PHP is authoritative. It may include a compatible libpq.dll and other runtime files that should not be mixed with files from another distribution.
Step 5: Enable the driver in the correct php.ini
Open the php.ini reported by php --ini, or the configuration shown by the web phpinfo() page.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesFind or add:
extension=pdo_pgsql
Older configurations may use:
extension=php_pdo_pgsql.dll
Also check:
extension_dir="C:pathtophpext"
Replace the example path with the actual PHP ext directory. Do not leave an incorrect old path from a previous PHP installation.
Save the file, then restart the relevant process:
- Restart Apache from its control panel.
- Restart the IIS website or application pool.
- Restart the PHP service used by the application.
- Close and reopen Command Prompt for CLI tests.
Run:
php -m | findstr /i "PDO pdo_pgsql"
A working configuration should show PDO and pdo_pgsql.
Step 6: Repair the PostgreSQL client dependency
PDO_PGSQL depends on PostgreSQL’s client library, including libpq.dll. The required library version depends on the PHP release, so do not assume that any libpq.dll will work.
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A common failure pattern is:
- The DLL exists in the PHP
extfolder. - CLI PHP works.
- Apache or IIS still reports that the module cannot be found.
That can happen because Apache or an IIS service account does not receive the same PATH as your interactive command prompt.
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Use the compatible client library supplied with the PHP or application package, or use an official PostgreSQL installation. Do not copy an arbitrary libpq.dll into System32.
If you change the system PATH:
- Press Windows key and search for environment variables.
- Select Edit the system environment variables.
- Click Environment Variables.
- Edit the appropriate
Pathentry. - Add the verified directory containing the compatible client library.
- Click OK through every dialog.
- Restart Apache, IIS, or the affected service.
A service may need a restart before it sees the updated environment. If the application runs under a restricted service account, make sure that account can access the required directory.
Step 7: Repair the Microsoft Visual C++ runtime
Official Windows PHP builds may require the Microsoft Visual C++ Redistributable. Install the package matching the PHP process architecture:
vc_redist.x64.exefor 64-bit PHPvc_redist.x86.exefor 32-bit PHP
To repair it:
- Open Settings.
- Select Apps.
- Choose Installed apps.
- Search for Microsoft Visual C++ Redistributable.
- Open the matching entry.
- Select Modify.
- Choose Repair.
If the correct package is not installed, obtain it from Microsoft’s official Visual C++ Redistributable download page. Older PHP releases may require an older compiler runtime, so match the runtime to the PHP build rather than installing random runtime packages.
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Step 8: Check Windows Security quarantine
If the file disappeared after an update or scan, check whether Windows Security quarantined it.
- Open Windows Security.
- Select Virus & threat protection.
- Click Protection history.
- Review recent actions involving the PHP folder.
- Restore the file only if it came from a verified PHP or application package.
- Rescan the restored file and the full application folder.
If you cannot verify the file’s origin, do not restore it. Reinstall the PHP or application package from its official source instead.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Step 9: Deal with unrelated device-driver problems correctly
Despite some generic DLL classifications, php_pdo_pgsql.dll is not a GPU, audio, chipset, printer, or other Windows hardware driver. Device Manager cannot repair this PHP extension.
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If Device Manager also shows a separate hardware problem:
- Right-click Start.
- Select Device Manager.
- Expand the relevant category.
- Right-click the device with the warning icon.
- Select Update driver.
- Choose Search automatically for drivers, or install the driver downloaded from the hardware manufacturer.
- Restart Windows.
- If the issue began after an update, open Properties, select the Driver tab, and choose Roll Back Driver when available.
Manually hunting through multiple hardware-driver versions can be time-consuming. Outbyte Driver Updater can scan for outdated drivers, while the full version performs the driver installation; it is not required to repair PHP, and the PHP package remains the definitive fix for this DLL.
Step 10: Repair broader Windows corruption only if needed
Because this is not a protected Windows system file, DISM and SFC are lower-probability fixes. Use them when several Windows components are failing or the runtime environment appears broadly corrupted.
Open Command Prompt as administrator:
- Press Windows key.
- Type
cmd. - Right-click Command Prompt.
- Select Run as administrator.
- Run:
DISM.exe /Online /Cleanup-image /Restorehealth
Wait for it to finish, then run:
sfc /scannow
Restart Windows afterward and test PHP again.
Repeating system scans without knowing what changed makes troubleshooting difficult. Outbyte PC Repair can scan for broader Windows issues and show what needs attention, while its repair functions require the full version; it is optional, and repairing the owning PHP package remains the direct fix.
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Do not:
- Download
php_pdo_pgsql.dllfrom a random DLL website. - Copy it into
C:WindowsSystem32orC:WindowsSysWOW64. - Rename another DLL to this filename.
- Mix a 32-bit DLL with 64-bit PHP.
- Mix Thread Safe and Non Thread Safe builds.
- Copy only one DLL from a different PHP version.
- Use
regsvr32on this file.
regsvr32 is for DLLs designed to expose a registration entry point such as DllRegisterServer. PHP extensions are loaded through php.ini and extension_dir, not registered like COM components.
Verify the repair
For command-line PHP, run:
php -m | findstr /i "PDO pdo_pgsql pgsql"
You should see PDO and pdo_pgsql.
For a web application, open a temporary phpinfo() page and confirm:
- The expected PHP installation is loaded.
extension_dirpoints to the correct folder.- A
pdo_pgsqlsection is present. - The PostgreSQL client library information is displayed.
Then test the application’s database connection. If CLI PHP works but the website does not, compare the web server’s phpinfo() output with php --ini; they are probably using different PHP runtimes or configuration files.
FAQ
Is php_pdo_pgsql.dll supplied by Windows?
No. It is supplied by PHP, a PHP bundle, or an application that embeds PHP.
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Do I need to install PostgreSQL Server?
Not necessarily. The extension needs PostgreSQL client components such as libpq.dll; the database server can be remote.
Why does pgsql not fix my PDO application?
pgsql and pdo_pgsql are separate extensions. PDO applications require pdo_pgsql.
Should I use Windows Features to enable it?
No Windows Feature normally enables this PHP driver. Enable it in the correct php.ini and repair the PHP package if necessary.
Should I run regsvr32 php_pdo_pgsql.dll?
No. PHP loads extensions through php.ini; regsvr32 is not the correct mechanism.
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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →What if the error started after an update?
Repair or reinstall the application or PHP bundle that owns the file. If antivirus quarantined it, restore only a verified package file after rescanning.
What if the application still fails after PHP is repaired?
Check the web server’s actual PHP runtime, php.ini, extension_dir, libpq.dll, Visual C++ runtime, architecture, and TS/NTS compatibility. If the application is packaged, its own repair or reinstall process is the final authority.
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