Method 1: Solving the DLL Error by Copying the Libpq721.dll File to the Windows System Folder 

1. The file you are going to download is a compressed file with the ".zip" extension. You cannot directly install the ".zip" file. First, you need to extract the dll file from inside it. So, double-click the file with the ".zip" extension that you downloaded and open the file.
2. You will see the file named "Libpq721.dll" in the window that opens up. This is the file we are going to install. Click the file once with the left mouse button. By doing this you will have chosen the file.

   

3. Click the "Extract To" symbol marked in the picture. To extract the dll file, it will want you to choose the desired location. Choose the "Desktop" location and click "OK" to extract the file to the desktop. In order to do this, you need to use the Winrar software. If you do not have this software, you can find and download it through a quick search on the Internet.

   

4. Copy the "Libpq721.dll" file and paste it into the "C:\Windows\System32" folder.

   

5. If your system is 64 Bit, copy the "Libpq721.dll" file and paste it into "C:\Windows\sysWOW64" folder.

   NOTE! On 64 Bit systems, you must copy the dll file to both the "sysWOW64" and "System32" folders. In other words, both folders need the "Libpq721.dll" file.

   

6. In order to run the Command Line as an administrator, complete the following steps.

   NOTE! In this explanation, we ran the Command Line on Windows 10. If you are using one of the Windows 8.1, Windows 8, Windows 7, Windows Vista or Windows XP operating systems, you can use the same methods to run the Command Line as an administrator. Even though the pictures are taken from Windows 10, the processes are similar.

   1. First, open the Start Menu and before clicking anywhere, type "cmd" but do not press Enter.
   2. When you see the "Command Line" option among the search results, hit the "CTRL" + "SHIFT" + "ENTER" keys on your keyboard.
   3. A window will pop up asking, "Do you want to run this process?". Confirm it by clicking to "Yes" button.

   

7. Let's copy the command below and paste it in the Command Line that comes up, then let's press Enter. This command deletes the Libpq721.dll file's problematic registry in the Windows Registry Editor (The file that we copied to the System32 folder does not perform any action with the file, it just deletes the registry in the Windows Registry Editor. The file that we pasted into the System32 folder will not be damaged).

   %windir%\System32\regsvr32.exe /u Libpq721.dll

   

8. If you have a 64 Bit operating system, after running the command above, you must run the command below. This command will clean the Libpq721.dll file's damaged registry in 64 Bit as well (The cleaning process will be in the registries in the Registry Editor< only. In other words, the dll file you paste into the SysWoW64 folder will stay as it).

   %windir%\SysWoW64\regsvr32.exe /u Libpq721.dll

   

9. We need to make a clean registry for the dll file's registry that we deleted from Regedit (Windows Registry Editor). In order to accomplish this, copy and paste the command below into the Command Line and press Enter key.

   %windir%\System32\regsvr32.exe /i Libpq721.dll

   

10. If you are using a Windows with 64 Bit architecture, after running the previous command, you need to run the command below. By running this command, we will have created a clean registry for the Libpq721.dll file (We deleted the damaged registry with the previous command).

    %windir%\SysWoW64\regsvr32.exe /i Libpq721.dll

    

11. If you did all the processes correctly, the missing dll file will have been installed. You may have made some mistakes when running the Command Line processes. Generally, these errors will not prevent the Libpq721.dll file from being installed. In other words, the installation will be completed, but it may give an error due to some incompatibility issues. You can try running the program that was giving you this dll file error after restarting your computer. If you are still getting the dll file error when running the program, please try the 2nd method.

Method 2: Copying the Libpq721.dll File to the Software File Folder 

1. First, you need to find the file folder for the software you are receiving the "Libpq721.dll not found", "Libpq721.dll is missing" or other similar dll errors. In order to do this, right-click on the shortcut for the software and click the Properties option from the options that come up.

   

2. Open the software's file folder by clicking on the Open File Location button in the Properties window that comes up.

   

3. Copy the Libpq721.dll file into this folder that opens.

   

4. This is all there is to the process. Now, try to run the software again. If the problem still is not solved, you can try the 3rd Method.

Method 3: Uninstalling and Reinstalling the Software that Gives You the Libpq721.dll Error 

1. Open the Run window by pressing the "Windows" + "R" keys on your keyboard at the same time. Type in the command below into the Run window and push Enter to run it. This command will open the "Programs and Features" window.

   appwiz.cpl

   

2. The softwares listed in the Programs and Features window that opens up are the softwares installed on your computer. Find the software that gives you the dll error and run the "Right-Click > Uninstall" command on this software.

   

3. Following the instructions that come up, uninstall the software from your computer and restart your computer.

   

4. 4. After restarting your computer, reinstall the software that was giving you the error.
5. You may be able to solve the dll error you are experiencing by using this method. If the error messages are continuing despite all these processes, we may have a problem deriving from Windows. To solve dll errors deriving from Windows, you need to complete the 4th Method and the 5th Method in the list.

Method 4: Solving the Libpq721.dll Error Using the Windows System File Checker 

1. In order to run the Command Line as an administrator, complete the following steps.

   NOTE! In this explanation, we ran the Command Line on Windows 10. If you are using one of the Windows 8.1, Windows 8, Windows 7, Windows Vista or Windows XP operating systems, you can use the same methods to run the Command Line as an administrator. Even though the pictures are taken from Windows 10, the processes are similar.

   1. First, open the Start Menu and before clicking anywhere, type "cmd" but do not press Enter.
   2. When you see the "Command Line" option among the search results, hit the "CTRL" + "SHIFT" + "ENTER" keys on your keyboard.
   3. A window will pop up asking, "Do you want to run this process?". Confirm it by clicking to "Yes" button.

   

2. Paste the command below into the Command Line that opens up and hit the Enter key.

   sfc /scannow

   

3. This process can take some time. You can follow its progress from the screen. Wait for it to finish and after it is finished try to run the software that was giving the dll error again.

Method 5: Fixing the Libpq721.dll Errors by Manually Updating Windows 

Some softwares require updated dll files from the operating system. If your operating system is not updated, this requirement is not met and you will receive dll errors. Because of this, updating your operating system may solve the dll errors you are experiencing.

Most of the time, operating systems are automatically updated. However, in some situations, the automatic updates may not work. For situations like this, you may need to check for updates manually.

For every Windows version, the process of manually checking for updates is different. Because of this, we prepared a special guide for each Windows version. You can get our guides to manually check for updates based on the Windows version you use through the links below.

Guides to Manually Update the Windows Operating System 

1. Guide to Manually Update Windows 10
2. Guide to Manually Update Windows 8.1 and Windows 8
3. Guide to Manually Update Windows 7 and Windows Vista
4. Guide to Manually Update Windows XP