diff --git a/internal/lsp/cache/view.go b/internal/lsp/cache/view.go
index aff5988c..8c05f45a 100644
--- a/internal/lsp/cache/view.go
+++ b/internal/lsp/cache/view.go
@@ -104,7 +104,7 @@ func (v *View) parse(uri source.URI) error {
 		}
 		return err
 	}
-
+	var foundPkg bool // true if we found a package for uri
 	for _, pkg := range pkgs {
 		if len(pkg.Syntax) == 0 {
 			return fmt.Errorf("no syntax trees for %s", pkg.PkgPath)
@@ -118,7 +118,13 @@ func (v *View) parse(uri source.URI) error {
 			f.token = fToken
 			f.ast = fAST
 			f.pkg = pkg
+			if fURI == uri {
+				foundPkg = true
+			}
 		}
 	}
+	if !foundPkg {
+		return fmt.Errorf("no package found for %v", uri)
+	}
 	return nil
 }
diff --git a/internal/lsp/diagnostics.go b/internal/lsp/diagnostics.go
index 49743dc0..c7149185 100644
--- a/internal/lsp/diagnostics.go
+++ b/internal/lsp/diagnostics.go
@@ -13,7 +13,10 @@ import (
 )
 
 func (s *server) cacheAndDiagnose(ctx context.Context, uri protocol.DocumentURI, content string) {
-	sourceURI := fromProtocolURI(uri)
+	sourceURI, err := fromProtocolURI(uri)
+	if err != nil {
+		return // handle error?
+	}
 	if err := s.setContent(ctx, sourceURI, []byte(content)); err != nil {
 		return // handle error?
 	}
diff --git a/internal/lsp/format.go b/internal/lsp/format.go
index 8a238099..ec0db161 100644
--- a/internal/lsp/format.go
+++ b/internal/lsp/format.go
@@ -10,7 +10,11 @@ import (
 
 // formatRange formats a document with a given range.
 func formatRange(ctx context.Context, v source.View, uri protocol.DocumentURI, rng *protocol.Range) ([]protocol.TextEdit, error) {
-	f, err := v.GetFile(ctx, fromProtocolURI(uri))
+	sourceURI, err := fromProtocolURI(uri)
+	if err != nil {
+		return nil, err
+	}
+	f, err := v.GetFile(ctx, sourceURI)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/imports.go b/internal/lsp/imports.go
index 32f3e1ca..2f8f7c1c 100644
--- a/internal/lsp/imports.go
+++ b/internal/lsp/imports.go
@@ -12,7 +12,11 @@ import (
 )
 
 func organizeImports(ctx context.Context, v source.View, uri protocol.DocumentURI) ([]protocol.TextEdit, error) {
-	f, err := v.GetFile(ctx, fromProtocolURI(uri))
+	sourceURI, err := fromProtocolURI(uri)
+	if err != nil {
+		return nil, err
+	}
+	f, err := v.GetFile(ctx, sourceURI)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/lsp/position.go b/internal/lsp/position.go
index 454eb31f..4b19c784 100644
--- a/internal/lsp/position.go
+++ b/internal/lsp/position.go
@@ -7,6 +7,7 @@ package lsp
 import (
 	"context"
 	"go/token"
+	"net/url"
 
 	"golang.org/x/tools/internal/lsp/cache"
 	"golang.org/x/tools/internal/lsp/protocol"
@@ -15,15 +16,23 @@ import (
 
 // fromProtocolURI converts a protocol.DocumentURI to a source.URI.
 // TODO(rstambler): Add logic here to support Windows.
-func fromProtocolURI(uri protocol.DocumentURI) source.URI {
-	return source.URI(uri)
+func fromProtocolURI(uri protocol.DocumentURI) (source.URI, error) {
+	unescaped, err := url.PathUnescape(string(uri))
+	if err != nil {
+		return "", err
+	}
+	return source.URI(unescaped), nil
 }
 
 // fromProtocolLocation converts from a protocol location to a source range.
 // It will return an error if the file of the location was not valid.
 // It uses fromProtocolRange to convert the start and end positions.
 func fromProtocolLocation(ctx context.Context, v *cache.View, loc protocol.Location) (source.Range, error) {
-	f, err := v.GetFile(ctx, fromProtocolURI(loc.URI))
+	sourceURI, err := fromProtocolURI(loc.URI)
+	if err != nil {
+		return source.Range{}, err
+	}
+	f, err := v.GetFile(ctx, sourceURI)
 	if err != nil {
 		return source.Range{}, err
 	}
diff --git a/internal/lsp/server.go b/internal/lsp/server.go
index 98510de7..2558da21 100644
--- a/internal/lsp/server.go
+++ b/internal/lsp/server.go
@@ -75,10 +75,19 @@ func (s *server) Initialize(ctx context.Context, params *protocol.InitializePara
 	s.snippetsSupported = params.Capabilities.TextDocument.Completion.CompletionItem.SnippetSupport
 	s.signatureHelpEnabled = true
 
-	rootPath, err := fromProtocolURI(*params.RootURI).Filename()
+	var rootURI protocol.DocumentURI
+	if params.RootURI != nil {
+		rootURI = *params.RootURI
+	}
+	sourceURI, err := fromProtocolURI(rootURI)
 	if err != nil {
 		return nil, err
 	}
+	rootPath, err := sourceURI.Filename()
+	if err != nil {
+		return nil, err
+	}
+
 	s.view = cache.NewView(&packages.Config{
 		Dir:     rootPath,
 		Mode:    packages.LoadSyntax,
@@ -180,12 +189,20 @@ func (s *server) DidSave(context.Context, *protocol.DidSaveTextDocumentParams) e
 }
 
 func (s *server) DidClose(ctx context.Context, params *protocol.DidCloseTextDocumentParams) error {
-	s.setContent(ctx, fromProtocolURI(params.TextDocument.URI), nil)
+	sourceURI, err := fromProtocolURI(params.TextDocument.URI)
+	if err != nil {
+		return err
+	}
+	s.setContent(ctx, sourceURI, nil)
 	return nil
 }
 
 func (s *server) Completion(ctx context.Context, params *protocol.CompletionParams) (*protocol.CompletionList, error) {
-	f, err := s.view.GetFile(ctx, fromProtocolURI(params.TextDocument.URI))
+	sourceURI, err := fromProtocolURI(params.TextDocument.URI)
+	if err != nil {
+		return nil, err
+	}
+	f, err := s.view.GetFile(ctx, sourceURI)
 	if err != nil {
 		return nil, err
 	}
@@ -209,7 +226,11 @@ func (s *server) CompletionResolve(context.Context, *protocol.CompletionItem) (*
 }
 
 func (s *server) Hover(ctx context.Context, params *protocol.TextDocumentPositionParams) (*protocol.Hover, error) {
-	f, err := s.view.GetFile(ctx, fromProtocolURI(params.TextDocument.URI))
+	sourceURI, err := fromProtocolURI(params.TextDocument.URI)
+	if err != nil {
+		return nil, err
+	}
+	f, err := s.view.GetFile(ctx, sourceURI)
 	if err != nil {
 		return nil, err
 	}
@@ -237,7 +258,11 @@ func (s *server) Hover(ctx context.Context, params *protocol.TextDocumentPositio
 }
 
 func (s *server) SignatureHelp(ctx context.Context, params *protocol.TextDocumentPositionParams) (*protocol.SignatureHelp, error) {
-	f, err := s.view.GetFile(ctx, fromProtocolURI(params.TextDocument.URI))
+	sourceURI, err := fromProtocolURI(params.TextDocument.URI)
+	if err != nil {
+		return nil, err
+	}
+	f, err := s.view.GetFile(ctx, sourceURI)
 	if err != nil {
 		return nil, err
 	}
@@ -254,7 +279,11 @@ func (s *server) SignatureHelp(ctx context.Context, params *protocol.TextDocumen
 }
 
 func (s *server) Definition(ctx context.Context, params *protocol.TextDocumentPositionParams) ([]protocol.Location, error) {
-	f, err := s.view.GetFile(ctx, fromProtocolURI(params.TextDocument.URI))
+	sourceURI, err := fromProtocolURI(params.TextDocument.URI)
+	if err != nil {
+		return nil, err
+	}
+	f, err := s.view.GetFile(ctx, sourceURI)
 	if err != nil {
 		return nil, err
 	}
@@ -271,7 +300,11 @@ func (s *server) Definition(ctx context.Context, params *protocol.TextDocumentPo
 }
 
 func (s *server) TypeDefinition(ctx context.Context, params *protocol.TextDocumentPositionParams) ([]protocol.Location, error) {
-	f, err := s.view.GetFile(ctx, fromProtocolURI(params.TextDocument.URI))
+	sourceURI, err := fromProtocolURI(params.TextDocument.URI)
+	if err != nil {
+		return nil, err
+	}
+	f, err := s.view.GetFile(ctx, sourceURI)
 	if err != nil {
 		return nil, err
 	}