@@ -251,8 +251,10 @@ let createDependenciesFileR (rootDirectory : DirectoryInfo) nugetEnv mode =
             if nugetEnv.NugetConfig.PackageSources = [] then [Constants.DefaultNugetStream,None] else nugetEnv.NugetConfig.PackageSources
             |> List.map (fun (n, auth) -> n, auth |> Option.map (CredsMigrationMode.toAuthentication mode n))
             |> List.map (fun source -> 
-                            try source |> PackageSource.Parse |> Rop.succeed
-                            with _ -> source |> fst |> PackageSourceParseError |> Rop.fail)
+                            try source |> PackageSource.Parse |> succeed
+                            with _ -> source |> fst |> PackageSourceParseError |> fail
+                            |> successTee PackageSource.warnIfNoConnection)
+                            
             |> Rop.collect
 
         sources
 
@@ -1,8 +1,11 @@
 module Paket.PackageSources
 
 open System
+open System.IO
 open System.Text.RegularExpressions
-open Logging
+
+open Paket.Logging
+open Paket.Rop
 
 type EnvironmentVariable = 
     { Variable : string
@@ -91,4 +94,15 @@ type PackageSource =
 
     static member NugetSource url = Nuget { Url = url; Authentication = None }
 
+    static member warnIfNoConnection (source,_) = 
+        match source with
+        | Nuget {Url = url; Authentication = auth} -> 
+            use client = Utils.createWebClient (auth |> Option.map toBasicAuth)
+            try client.DownloadData url |> ignore 
+            with _ ->
+                traceWarnfn "Unable to ping remote Nuget feed: %s." url
+        | LocalNuget path -> 
+            if not <| File.Exists path then 
+                traceWarnfn "Local Nuget feed doesn't exist: %s." path            
+
 let DefaultNugetSource = PackageSource.NugetSource Constants.DefaultNugetStream