diff --git a/main.go b/main.go
index a46be4e..7f3d8e0 100644
--- a/main.go
+++ b/main.go
@@ -74,6 +74,7 @@ type request struct {
 	Submissions                      []submissionType `json:"submissions"`                      // Data for submitted libraries.
 	IndexEntry                       string           `json:"indexEntry"`                       // Entry that will be made to the Library Manager index source file when the submission is accepted.
 	IndexerLogsURLs                  string           `json:"indexerLogsURLs"`                  // List of URLs where the logs from the Library Manager indexer for each submission are available for view.
+	Error                            string           `json:"error"`                            // Error message.
 }
 
 // submissionType is the type of the data for each individual library submitted in the request.
@@ -127,7 +128,7 @@ func main() {
 	}
 	var req request
 	var submissionURLs []string
-	req.Type, req.ArduinoLintLibraryManagerSetting, submissionURLs = parseDiff(rawDiff, *listNameArgument)
+	req.Type, req.Error, req.ArduinoLintLibraryManagerSetting, submissionURLs = parseDiff(rawDiff, *listNameArgument)
 
 	// Process the submissions.
 	var indexEntries []string
@@ -177,10 +178,16 @@ func errorExit(message string) {
 	os.Exit(1)
 }
 
-// parseDiff parses the request diff and returns the request type, `arduino-lint --library-manager` setting, and list of submission URLs.
-func parseDiff(rawDiff []byte, listName string) (string, string, []string) {
+// parseDiff parses the request diff and returns the request type, request error, `arduino-lint --library-manager` setting, and list of submission URLs.
+func parseDiff(rawDiff []byte, listName string) (string, string, string, []string) {
 	var submissionURLs []string
 
+	// Check if the PR has removed the final newline from a file, which would cause a spurious diff for the next PR if merged.
+	// Unfortunately, the diff package does not have this capability (only to detect missing newline in the original file).
+	if bytes.Contains(rawDiff, []byte("\\ No newline at end of file")) {
+		return "invalid", "Pull request removes newline from the end of a file.%0APlease add a blank line to the end of the file.", "", nil
+	}
+
 	diffs, err := diff.ParseMultiFileDiff(rawDiff)
 	if err != nil {
 		panic(err)
@@ -188,7 +195,7 @@ func parseDiff(rawDiff []byte, listName string) (string, string, []string) {
 
 	if (len(diffs) != 1) || (diffs[0].OrigName[2:] != listName) || (diffs[0].OrigName[2:] != diffs[0].NewName[2:]) { // Git diffs have a a/ or b/ prefix on file names.
 		// This is not a Library Manager submission.
-		return "other", "", nil
+		return "other", "", "", nil
 	}
 
 	var addedCount int
@@ -227,7 +234,7 @@ func parseDiff(rawDiff []byte, listName string) (string, string, []string) {
 		arduinoLintLibraryManagerSetting = "update"
 	}
 
-	return requestType, arduinoLintLibraryManagerSetting, submissionURLs
+	return requestType, "", arduinoLintLibraryManagerSetting, submissionURLs
 }
 
 // populateSubmission does the checks on the submission that aren't provided by Arduino Lint and gathers the necessary data on it.
diff --git a/main_test.go b/main_test.go
index e18c1eb..b4da57e 100644
--- a/main_test.go
+++ b/main_test.go
@@ -46,8 +46,9 @@ index cff484d..e14c179 100644
 +https://github.com/foo/bar
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs := parseDiff(diff, "repositories.txt")
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs := parseDiff(diff, "repositories.txt")
 	assert.Equal(t, "other", requestType, testName)
+	assert.Equal(t, "", requestError, testName)
 	assert.Equal(t, "", arduinoLintLibraryManagerSetting, testName)
 	assert.Nil(t, submissionURLs, testName)
 
@@ -62,8 +63,9 @@ index d4edde0..807b76d 100644
 +hello
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
 	assert.Equal(t, "other", requestType, testName)
+	assert.Equal(t, "", requestError, testName)
 	assert.Equal(t, "", arduinoLintLibraryManagerSetting, testName)
 	assert.Nil(t, submissionURLs, testName)
 
@@ -80,8 +82,9 @@ index cff484d..e14c179 100644
 +https://github.com/foo/bar
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
 	assert.Equal(t, "other", requestType, testName)
+	assert.Equal(t, "", requestError, testName)
 	assert.Equal(t, "", arduinoLintLibraryManagerSetting, testName)
 	assert.Nil(t, submissionURLs, testName)
 
@@ -96,8 +99,9 @@ index cff484d..9f67763 100644
 +https://github.com/foo/baz
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
 	assert.Equal(t, "submission", requestType, testName)
+	assert.Equal(t, "", requestError, testName)
 	assert.Equal(t, "submit", arduinoLintLibraryManagerSetting, testName)
 	assert.ElementsMatch(t, submissionURLs, []string{"https://github.com/foo/bar", "https://github.com/foo/baz"}, testName)
 
@@ -112,10 +116,11 @@ index cff484d..1b0b80b 100644
 \ No newline at end of file
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
-	assert.Equal(t, "submission", requestType, testName)
-	assert.Equal(t, "submit", arduinoLintLibraryManagerSetting, testName)
-	assert.ElementsMatch(t, submissionURLs, []string{"https://github.com/foo/bar"}, testName)
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
+	assert.Equal(t, "invalid", requestType, testName)
+	assert.Equal(t, "Pull request removes newline from the end of a file.%0APlease add a blank line to the end of the file.", requestError, testName)
+	assert.Equal(t, "", arduinoLintLibraryManagerSetting, testName)
+	assert.Nil(t, submissionURLs, testName)
 
 	testName = "Submission w/ blank line"
 	diff = []byte(`
@@ -125,11 +130,12 @@ index cff484d..1b0b80b 100644
 +++ b/repositories.txt
 @@ -3391,0 +3392 @@ https://github.com/lbernstone/plotutils
 +https://github.com/foo/bar
-\ No newline at end of file
++
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
 	assert.Equal(t, "submission", requestType, testName)
+	assert.Equal(t, "", requestError, testName)
 	assert.Equal(t, "submit", arduinoLintLibraryManagerSetting, testName)
 	assert.ElementsMatch(t, submissionURLs, []string{"https://github.com/foo/bar"}, testName)
 
@@ -143,8 +149,9 @@ index cff484d..38e11d8 100644
 -https://github.com/arduino-libraries/Ethernet
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
 	assert.Equal(t, "removal", requestType, testName)
+	assert.Equal(t, "", requestError, testName)
 	assert.Equal(t, "", arduinoLintLibraryManagerSetting, testName)
 	assert.Nil(t, submissionURLs, testName)
 
@@ -159,8 +166,9 @@ index cff484d..8b401a1 100644
 +https://github.com/foo/bar
 `)
 
-	requestType, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
+	requestType, requestError, arduinoLintLibraryManagerSetting, submissionURLs = parseDiff(diff, "repositories.txt")
 	assert.Equal(t, "modification", requestType, testName)
+	assert.Equal(t, "", requestError, testName)
 	assert.Equal(t, "update", arduinoLintLibraryManagerSetting, testName)
 	assert.Equal(t, submissionURLs, []string{"https://github.com/foo/bar"}, testName)
 }
diff --git a/test/test_all.py b/test/test_all.py
index b9b357e..449c3e8 100644
--- a/test/test_all.py
+++ b/test/test_all.py
@@ -21,16 +21,30 @@
 
 
 @pytest.mark.parametrize(
-    "repopath_folder_name, expected_type, expected_submissions, expected_indexentry, expected_indexerlogsurls",
+    "repopath_folder_name,"
+    "expected_type,"
+    "expected_error,"
+    "expected_submissions,"
+    "expected_indexentry,"
+    "expected_indexerlogsurls",
     [
-        ("list-deleted-diff", "other", None, "", ""),
-        ("multi-file-diff", "other", None, "", ""),
-        ("non-list-diff", "other", None, "", ""),
-        ("list-rename-diff", "other", None, "", ""),
-        ("removal", "removal", None, "", ""),
+        ("list-deleted-diff", "other", "", None, "", ""),
+        ("multi-file-diff", "other", "", None, "", ""),
+        ("non-list-diff", "other", "", None, "", ""),
+        ("list-rename-diff", "other", "", None, "", ""),
+        (
+            "no-final-newline-diff",
+            "invalid",
+            "Pull request removes newline from the end of a file.%0APlease add a blank line to the end of the file.",
+            None,
+            "",
+            "",
+        ),
+        ("removal", "removal", "", None, "", ""),
         (
             "modification",
             "modification",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/arduino-libraries/ArduinoCloudThing",
@@ -48,6 +62,7 @@
         (
             "url-error",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "foo",
@@ -65,6 +80,7 @@
         (
             "url-404",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "http://httpstat.us/404",
@@ -82,6 +98,7 @@
         (
             "not-supported-git-host",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://example.com",
@@ -101,6 +118,7 @@
         (
             "not-git-clone-url",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/arduino-libraries/ArduinoCloudThing/releases",
@@ -119,6 +137,7 @@
         (
             "already-in-library-manager",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/arduino-libraries/Servo",
@@ -136,6 +155,7 @@
         (
             "type-arduino",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/arduino-libraries/ArduinoCloudThing",
@@ -153,6 +173,7 @@
         (
             "type-partner",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/ms-iot/virtual-shields-arduino",
@@ -170,6 +191,7 @@
         (
             "type-recommended",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/adafruit/Adafruit_TinyFlash",
@@ -187,6 +209,7 @@
         (
             "type-contributed",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/sparkfun/SparkFun_Ublox_Arduino_Library",
@@ -205,6 +228,7 @@
         (
             "no-tags",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/arduino/cloud-examples",
@@ -224,6 +248,7 @@
         (
             "no-library-properties",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/arduino-libraries/WiFiLink-Firmware",
@@ -242,6 +267,7 @@
         (
             "duplicates-in-submission",
             "submission",
+            "",
             [
                 {
                     "submissionURL": "https://github.com/arduino-libraries/ArduinoCloudThing",
@@ -273,6 +299,7 @@ def test_request(
     run_command,
     repopath_folder_name,
     expected_type,
+    expected_error,
     expected_submissions,
     expected_indexentry,
     expected_indexerlogsurls,
@@ -286,6 +313,7 @@ def test_request(
 
     request = json.loads(result.stdout)
     assert request["type"] == expected_type
+    assert request["error"] == expected_error
     assert request["submissions"] == expected_submissions
     assert request["indexEntry"] == expected_indexentry
     assert request["submissions"] == expected_submissions
diff --git a/test/testdata/no-final-newline-diff/diff.txt b/test/testdata/no-final-newline-diff/diff.txt
new file mode 100644
index 0000000..390690b
--- /dev/null
+++ b/test/testdata/no-final-newline-diff/diff.txt
@@ -0,0 +1,9 @@
+diff --git a/repositories.txt b/repositories.txt
+index c080a7a..dcba162 100644
+--- a/repositories.txt
++++ b/repositories.txt
+@@ -1,2 +1,3 @@
+ https://github.com/arduino-libraries/Servo
+ https://github.com/arduino-libraries/Stepper
++https://github.com/arduino-libraries/ArduinoCloudThing
+\ No newline at end of file
diff --git a/test/testdata/no-final-newline-diff/repositories.txt b/test/testdata/no-final-newline-diff/repositories.txt
new file mode 100644
index 0000000..c080a7a
--- /dev/null
+++ b/test/testdata/no-final-newline-diff/repositories.txt
@@ -0,0 +1,2 @@
+https://github.com/arduino-libraries/Servo
+https://github.com/arduino-libraries/Stepper