diff --git a/src/main/kotlin/bandcampcollectiondownloader/BandcampCollectionDownloader.kt b/src/main/kotlin/bandcampcollectiondownloader/BandcampCollectionDownloader.kt
index 16ceb07..5f06568 100644
--- a/src/main/kotlin/bandcampcollectiondownloader/BandcampCollectionDownloader.kt
+++ b/src/main/kotlin/bandcampcollectiondownloader/BandcampCollectionDownloader.kt
@@ -1,6 +1,7 @@
 package bandcampcollectiondownloader
 
 import com.google.gson.Gson
+import com.google.gson.JsonSyntaxException
 import com.google.gson.annotations.SerializedName
 import org.jsoup.Jsoup
 import org.zeroturnaround.zip.ZipUtil
@@ -42,6 +43,12 @@ data class ParsedStatDownload(
 fun parsedCookiesToMap(parsedCookies: Array<ParsedCookie>): Map<String, String> {
     val result = HashMap<String, String>()
     for (parsedCookie in parsedCookies) {
+        if (parsedCookie.contentRaw == null) {
+            throw BandCampDownloaderError("Missing 'Content raw' field in cookie number ${parsedCookies.indexOf(parsedCookie) + 1}.")
+        }
+        if (parsedCookie.nameRaw == null) {
+            throw BandCampDownloaderError("Missing 'Name raw' field in cookie number ${parsedCookies.indexOf(parsedCookie) + 1}.")
+        }
         result.put(parsedCookie.nameRaw, parsedCookie.contentRaw)
     }
     return result
@@ -109,7 +116,12 @@ fun downloadAll(cookiesFile: Path, bandcampUser: String, downloadFormat: String,
         throw BandCampDownloaderError("Cookies file '$cookiesFile' cannot be found.")
     }
     val jsonData = String(Files.readAllBytes(cookiesFile))
-    val parsedCookies = gson.fromJson(jsonData, Array<ParsedCookie>::class.java)
+    val parsedCookies =
+            try {
+                gson.fromJson(jsonData, Array<ParsedCookie>::class.java)
+            } catch (e: JsonSyntaxException) {
+                throw BandCampDownloaderError("Cookies file '$cookiesFile' is not well formed: ${e.message}")
+            }
     val cookies = parsedCookiesToMap(parsedCookies)
 
     // Get collection page with cookies, hence with download links
diff --git a/src/test/kotlin/bandcampcollectiodownloader/test/BandcampCollectionDownloaderTests.kt b/src/test/kotlin/bandcampcollectiodownloader/test/BandcampCollectionDownloaderTests.kt
new file mode 100644
index 0000000..3034641
--- /dev/null
+++ b/src/test/kotlin/bandcampcollectiodownloader/test/BandcampCollectionDownloaderTests.kt
@@ -0,0 +1,42 @@
+package bandcampcollectiodownloader.test
+
+import bandcampcollectiondownloader.BandCampDownloaderError
+import bandcampcollectiondownloader.downloadAll
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import java.nio.file.Paths
+
+/**
+ * Note: bli is a valid bandcamp user (completely randomly chosen),
+ * but for which we have no credentials (ie. valid cookies).
+ */
+class BandcampCollectionDownloaderTests {
+
+    @Test
+    fun testErrorCookiesFileNotFound() {
+        assertThrows<BandCampDownloaderError> {
+            downloadAll(Paths.get("bli"),"bli","bli", Paths.get("bli"))
+        }
+    }
+
+    @Test
+    fun testErrorCookiesFileInvalidJson() {
+        assertThrows<BandCampDownloaderError> {
+            downloadAll(Paths.get("./test-data/notjsoncookies.json"),"bli","bli", Paths.get("bli"))
+        }
+    }
+
+    @Test
+    fun testErrorCookiesFileInvalidContent_wrongkey() {
+        //assertThrows<BandCampDownloaderError> {
+            downloadAll(Paths.get("./test-data/invalidcookies_wrongkeys.json"),"bli","bli", Paths.get("bli"))
+        //}
+    }
+
+    @Test
+    fun testErrorCookiesFileInvalidContent_noarray() {
+        //assertThrows<BandCampDownloaderError> {
+        downloadAll(Paths.get("./test-data/invalidcookies_noarray.json"),"bli","bli", Paths.get("bli"))
+        //}
+    }
+}
\ No newline at end of file
diff --git a/test-data/invalidcookies_noarray.json b/test-data/invalidcookies_noarray.json
new file mode 100644
index 0000000..a55db6e
--- /dev/null
+++ b/test-data/invalidcookies_noarray.json
@@ -0,0 +1,3 @@
+{
+	"hello" : 123
+}
\ No newline at end of file
diff --git a/test-data/invalidcookies_wrongkeys.json b/test-data/invalidcookies_wrongkeys.json
new file mode 100644
index 0000000..33c01d0
--- /dev/null
+++ b/test-data/invalidcookies_wrongkeys.json
@@ -0,0 +1,3 @@
+[{
+	"hello" : 123
+}]
\ No newline at end of file
diff --git a/test-data/notjsoncookies.json b/test-data/notjsoncookies.json
new file mode 100644
index 0000000..7a8fb35
--- /dev/null
+++ b/test-data/notjsoncookies.json
@@ -0,0 +1 @@
+Nope, not json.
\ No newline at end of file