求助：.NET Framework 4.0下ODBC连接PostgreSQL报错数据源未找到

Hey there, let's work through this ODBC connection issue you're hitting after downgrading to .NET Framework 4.0. That error message usually points to a mismatch between your setup and what the runtime expects, so let's break down the most likely fixes step by step:

First off, make sure your PostgreSQL ODBC driver plays nice with .NET 4.0. Some newer driver versions might prioritize support for later .NET releases, so you might need to use an older, .NET 4.0-compatible build (like psqlODBC 10.x or earlier).

Also, watch out for 32-bit/64-bit mismatches:

• If your project targets x86, you need the 32-bit ODBC driver installed
• If it targets x64, go with the 64-bit driver
• Avoid "Any CPU" if you can—this can cause the runtime to pick a bitness that doesn't match your driver

That error often pops up when the DSN you're referencing doesn't exist (or the runtime can't see it). Here's how to confirm:

• If you're using a 32-bit app, open the 32-bit ODBC Data Source Manager by running C:\Windows\SysWOW64\odbcad32.exe (the default System32 version is 64-bit and won't show 32-bit DSNs)
• For 64-bit apps, use C:\Windows\System32\odbcad32.exe
• Check that the DSN name in your connection string exactly matches what's configured here (case doesn't matter on Windows, but it's safest to match exactly)

If you're using a DSN-less connection string, ensure the driver name is correct. You can find the exact driver name in the "Drivers" tab of the ODBC Manager. For example, a valid DSN-less string might look like:

string connString = "Driver={PostgreSQL Unicode};Server=your-server;Port=5432;Database=your-db;Uid=your-user;Pwd=your-pass;";

Replace {PostgreSQL Unicode} with the exact name shown in your ODBC driver list (it might vary slightly by version, like PostgreSQL ODBC Driver(UNICODE)).

.NET Framework 4.0 supports ODBC, but make sure your project has the correct reference:

• Right-click your project in Visual Studio → Add Reference
• Find and select System.Data.Odbc (version 4.0.0.0) and click OK
• Double-check that the reference isn't marked as "missing" in your project references list

Sometimes downgrading .NET can mess up driver registration. Try uninstalling your current PostgreSQL ODBC driver, then download a .NET 4.0-compatible version (match the bitness to your project), and reinstall it. This ensures the driver is properly registered for .NET 4.0's runtime.

Give these steps a shot—odds are it's one of these mismatches causing the problem. Let me know if you run into any specific roadblocks!

内容的提问来源于stack exchange，提问作者user9095135