diff --git a/src/Paket.Core/PaketConfigFiles/ProjectFile.fs b/src/Paket.Core/PaketConfigFiles/ProjectFile.fs
index c7fac7430c..eeff28f21f 100644
--- a/src/Paket.Core/PaketConfigFiles/ProjectFile.fs
+++ b/src/Paket.Core/PaketConfigFiles/ProjectFile.fs
@@ -1069,6 +1069,20 @@ module ProjectFile =
         |> Array.map (fun x -> x.Trim())
         |> Array.toList
 
+    // Same as getTargetFramework/getTargetFrameworksParsed above but evaluates conditional
+    // PropertyGroups (e.g. `Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'"`)
+    // using the given Configuration/Platform, instead of an empty property map.
+    let getTargetFrameworkWithDefaults defaultProperties (project:ProjectFile) =
+        getPropertyWithDefaults "TargetFramework" defaultProperties project
+
+    let getTargetFrameworksParsedWithDefaults defaultProperties (project:ProjectFile) =
+        getPropertyWithDefaults "TargetFrameworks" defaultProperties project
+        |> Option.map (fun x -> x.Split([|';'|],StringSplitOptions.RemoveEmptyEntries))
+        |> Option.toArray
+        |> Array.concat
+        |> Array.map (fun x -> x.Trim())
+        |> Array.toList
+
     let getToolsVersion (project:ProjectFile) =
         let adjustIfWeHaveSDK v =
             try
@@ -1622,22 +1636,28 @@ module ProjectFile =
         sprintf "%s.%s" assemblyName ending
 
     let getOutputDirectory buildConfiguration buildPlatform (targetProfile : TargetProfile option) (project:ProjectFile) =
+        // Some projects put TargetFramework(s) inside a conditional PropertyGroup keyed on
+        // Configuration/Platform (e.g. `Condition="'$(Configuration)'=='Release'"`), so we must
+        // evaluate the property map with the requested Configuration/Platform, not an empty one,
+        // or the frameworks won't be found at all (see issue #3799).
+        let defaultProperties =
+            Map.ofList [("Configuration", buildConfiguration); ("Platform", buildPlatform)]
         let targetFramework =
             match targetProfile with
             | Some targetProfile ->
                 let targetProfile = targetProfile.ToString()
-                match getTargetFramework project with
+                match getTargetFrameworkWithDefaults defaultProperties project with
                 | Some x -> if x = targetProfile then x else ""
                 | None ->
-                    let parsedTargetFrameworks = getTargetFrameworksParsed project
+                    let parsedTargetFrameworks = getTargetFrameworksParsedWithDefaults defaultProperties project
                     match List.tryFind ((=) targetProfile) parsedTargetFrameworks with
                     | Some x -> x
                     | None -> ""
             | None ->
-                match getTargetFramework project with
+                match getTargetFrameworkWithDefaults defaultProperties project with
                 | Some x -> x
                 | None ->
-                    match getTargetFrameworksParsed project with
+                    match getTargetFrameworksParsedWithDefaults defaultProperties project with
                     | fwk :: _ -> fwk
                     | [] -> ""
 
diff --git a/tests/Paket.Tests/Paket.Tests.fsproj b/tests/Paket.Tests/Paket.Tests.fsproj
index 0ff0e05548..2beb860531 100644
--- a/tests/Paket.Tests/Paket.Tests.fsproj
+++ b/tests/Paket.Tests/Paket.Tests.fsproj
@@ -130,6 +130,8 @@
     <Compile Include="LocalFile\LocalFileSpecs.fs" />
     <Compile Include="Simplifier\BasicScenarioSpecs.fs" />
     <TestAsset Include="ProjectFile\TestData\MicrosoftNetSdkWithTargetFrameworkAndOutputPath.csprojtest" />
+    <TestAsset Include="ProjectFile\TestData\MicrosoftNetSdkWithConditionalTargetFrameworks.csprojtest" />
+    <TestAsset Include="ProjectFile\TestData\MicrosoftNetSdkWithConditionalTargetFrameworksOnly.csprojtest" />
     <TestAsset Include="ProjectFile\TestData\EmptyFsharpGuid.fsprojtest" />
     <TestAsset Include="ProjectFile\TestData\EmptyVbGuid.vbprojtest" />
     <TestAsset Include="ProjectFile\TestData\EmptyPyGuid.pyprojtest" />
diff --git a/tests/Paket.Tests/ProjectFile/OutputSpecs.fs b/tests/Paket.Tests/ProjectFile/OutputSpecs.fs
index 88b95a32ed..7ab8f22034 100644
--- a/tests/Paket.Tests/ProjectFile/OutputSpecs.fs
+++ b/tests/Paket.Tests/ProjectFile/OutputSpecs.fs
@@ -103,6 +103,48 @@ let ``should detect output path for netsdk with outputPath and appendTargetFrame
     let expected = (System.IO.Path.Combine(@"bin", configuration,"netstandard1.4_bin") |> normalizePath)
     outPath.ToLowerInvariant() |> shouldEqual (expected.ToLowerInvariant())
 
+[<Test>]
+let ``should detect output path for netsdk with conditional target frameworks csproj file``
+        ([<Values("Debug", "Release", "dEbUg", "rElEaSe")>] configuration) =
+    ensureDir ()
+    let projectFile = ProjectFile.TryLoad("./ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworks.csprojtest").Value
+    // Should not throw "Unable to find <configuration> output path node" (see issue #3799)
+    let outPath = projectFile.GetOutputDirectory configuration "" None
+    outPath |> shouldNotEqual ""
+
+[<Test>]
+let ``should detect output path for netsdk with only conditional target frameworks (no unconditional fallback) csproj file``
+        ([<Values("Debug", "Release")>] configuration) =
+    ensureDir ()
+    // Reproduces the exact shape from issue #3799: no unconditional TargetFramework/TargetFrameworks
+    // element exists at all, only Configuration-conditioned PropertyGroups.
+    let projectFile = ProjectFile.TryLoad("./ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworksOnly.csprojtest").Value
+    let outPath = projectFile.GetOutputDirectory configuration "" None
+    outPath |> shouldNotEqual ""
+
+[<Test>]
+let ``should pick the conditional target frameworks matching the requested configuration for netsdk csproj file``
+        ([<Values("Debug", "Release")>] configuration) =
+    ensureDir ()
+    let projectFile = ProjectFile.TryLoad("./ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworksOnly.csprojtest").Value
+    let outPath = projectFile.GetOutputDirectory configuration "" None
+    // Debug config only lists netstandard2.0;net45, Release additionally lists net47;
+    // the first framework in each list is netstandard2.0, and it should be selected as the default.
+    let expected = (System.IO.Path.Combine(@"bin", configuration, "netstandard2.0") |> normalizePath)
+    outPath.ToLowerInvariant() |> shouldEqual (expected.ToLowerInvariant())
+
+[<Test>]
+let ``should detect output path for a specific target profile in a conditional target frameworks csproj file``
+        ([<Values("Debug", "Release")>] configuration) =
+    ensureDir ()
+    let projectFile = ProjectFile.TryLoad("./ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworksOnly.csprojtest").Value
+    let targetProfile =
+        FrameworkDetection.internalExtract "net45"
+        |> Option.map TargetProfile.SinglePlatform
+    let outPath = projectFile.GetOutputDirectory configuration "" targetProfile
+    let expected = (System.IO.Path.Combine(@"bin", configuration, "net45") |> normalizePath)
+    outPath.ToLowerInvariant() |> shouldEqual (expected.ToLowerInvariant())
+
 [<Test>]
 let ``should detect framework profile for ProjectWithConditions file`` () =
     ensureDir ()
diff --git a/tests/Paket.Tests/ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworks.csprojtest b/tests/Paket.Tests/ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworks.csprojtest
new file mode 100644
index 0000000000..23350487da
--- /dev/null
+++ b/tests/Paket.Tests/ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworks.csprojtest
@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <AssemblyName>TestPaket</AssemblyName>
+    <TargetFramework>netstandard2.0</TargetFramework>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)'=='Debug'">
+    <TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)'=='Release'">
+    <TargetFrameworks>netstandard2.0;net45;net47</TargetFrameworks>
+  </PropertyGroup>
+</Project>
diff --git a/tests/Paket.Tests/ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworksOnly.csprojtest b/tests/Paket.Tests/ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworksOnly.csprojtest
new file mode 100644
index 0000000000..7b87c3d03c
--- /dev/null
+++ b/tests/Paket.Tests/ProjectFile/TestData/MicrosoftNetSdkWithConditionalTargetFrameworksOnly.csprojtest
@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup Condition="'$(Configuration)'=='Debug'">
+    <TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)'=='Release'">
+    <TargetFrameworks>netstandard2.0;net45;net47</TargetFrameworks>
+  </PropertyGroup>
+</Project>