diff --git a/src/api/core/ciphers.rs b/src/api/core/ciphers.rs
index 3aa4f9d7..b3dca3b6 100644
--- a/src/api/core/ciphers.rs
+++ b/src/api/core/ciphers.rs
@@ -1123,12 +1123,12 @@ async fn save_attachment(
         // the client. Upstream allows +/- 1 MiB deviation from this
         // size, but it's not clear when or why this is needed.
         const LEEWAY: i64 = 1024 * 1024; // 1 MiB
-        let Some(min_size) = attachment.file_size.checked_add(LEEWAY) else {
-            err!("Invalid attachment size min")
-        };
-        let Some(max_size) = attachment.file_size.checked_sub(LEEWAY) else {
+        let Some(max_size) = attachment.file_size.checked_add(LEEWAY) else {
             err!("Invalid attachment size max")
         };
+        let Some(min_size) = attachment.file_size.checked_sub(LEEWAY) else {
+            err!("Invalid attachment size min")
+        };
 
         if min_size <= size && size <= max_size {
             if size != attachment.file_size {
diff --git a/src/config.rs b/src/config.rs
index e99518a7..2f0e9264 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -778,12 +778,15 @@ fn validate_config(cfg: &ConfigItems) -> Result<(), Error> {
         }
     }
 
+    // TODO: deal with deprecated flags so they can be removed from this list, cf. #4263
     const KNOWN_FLAGS: &[&str] =
         &["autofill-overlay", "autofill-v2", "browser-fileless-import", "fido2-vault-credentials"];
-    for flag in parse_experimental_client_feature_flags(&cfg.experimental_client_feature_flags).keys() {
-        if !KNOWN_FLAGS.contains(&flag.as_str()) {
-            warn!("The experimental client feature flag {flag:?} is unrecognized. Please ensure the feature flag is spelled correctly and that it is supported in this version.");
-        }
+    let configured_flags = parse_experimental_client_feature_flags(&cfg.experimental_client_feature_flags);
+    let invalid_flags: Vec<_> = configured_flags.keys().filter(|flag| !KNOWN_FLAGS.contains(&flag.as_str())).collect();
+    if !invalid_flags.is_empty() {
+        err!(format!("Unrecognized experimental client feature flags: {invalid_flags:?}.\n\n\
+                     Please ensure all feature flags are spelled correctly and that they are supported in this version.\n\
+                     Supported flags: {KNOWN_FLAGS:?}"));
     }
 
     const MAX_FILESIZE_KB: i64 = i64::MAX >> 10;