diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 3e285021bd..c38c3e7c14 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -3323,6 +3323,13 @@ int journal_file_open(
         }
 
         r = mmap_cache_get(f->mmap, f->cache_fd, f->prot, CONTEXT_HEADER, true, 0, PAGE_ALIGN(sizeof(Header)), &f->last_stat, &h, NULL);
+        if (r == -EINVAL) {
+                /* Some file systems (jffs2 or p9fs) don't support mmap() properly (or only read-only
+                 * mmap()), and return EINVAL in that case. Let's propagate that as a more recognizable error
+                 * code. */
+                r = -EAFNOSUPPORT;
+                goto fail;
+        }
         if (r < 0)
                 goto fail;
 
diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c
index 51e7dedad5..414571191f 100644
--- a/src/journal/journald-server.c
+++ b/src/journal/journald-server.c
@@ -787,6 +787,10 @@ static bool shall_try_append_again(JournalFile *f, int r) {
                 log_warning("%s: Journal file is from the future, rotating.", f->path);
                 return true;
 
+        case -EAFNOSUPPORT:
+                log_warning("%s: underlying file system does not support memory mapping or another required file system feature.", f->path);
+                return false;
+
         default:
                 return false;
         }