diff --git a/rust/gui-client/src-common/src/auth.rs b/rust/gui-client/src-common/src/auth.rs
index 778a890d6..7623a30a2 100644
--- a/rust/gui-client/src-common/src/auth.rs
+++ b/rust/gui-client/src-common/src/auth.rs
@@ -28,8 +28,13 @@ pub enum Error {
     PathWrong,
     #[error("Couldn't read session file: {0}")]
     ReadFile(std::io::Error),
-    #[error("Could not (de)serialize session data")]
-    Serde,
+    #[error("Could not serialize session data")]
+    SerializeSession(#[source] serde_json::Error),
+    #[error("Could not deserialize session data ({json})")]
+    DeserializeSession {
+        source: serde_json::Error,
+        json: String,
+    },
     #[error("State in server response doesn't match state in client request")]
     StatesDontMatch,
     #[error("Couldn't write session file: {0}")]
@@ -212,7 +217,7 @@ impl Auth {
         save_file(
             &session_data_path()?,
             serde_json::to_string(session)
-                .map_err(|_| Error::Serde)?
+                .map_err(Error::SerializeSession)?
                 .as_bytes(),
         )?;
         Ok(())
@@ -248,8 +253,9 @@ impl Auth {
             Err(e) => return Err(Error::ReadFile(e)),
         };
         match std::fs::read_to_string(session_data_path()?) {
-            Ok(x) => {
-                session = serde_json::from_str(&x).map_err(|_| Error::Serde)?;
+            Ok(json) => {
+                session = serde_json::from_str(&json)
+                    .map_err(|source| Error::DeserializeSession { source, json })?;
             }
             Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
             Err(e) => return Err(Error::ReadFile(e)),