diff --git a/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/h2/V7.6_2026.08.11__Normalize_metadata_language.sql b/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/h2/V7.6_2026.08.11__Normalize_metadata_language.sql
new file mode 100644
index 00000000000..66593f23601
--- /dev/null
+++ b/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/h2/V7.6_2026.08.11__Normalize_metadata_language.sql
@@ -0,0 +1,34 @@
+--
+-- The contents of this file are subject to the license and copyright
+-- detailed in the LICENSE and NOTICE files at the root of the source
+-- tree and available online at
+--
+-- http://www.dspace.org/license/
+--
+
+-- ufal/clarin-dspace#1406
+--
+-- Metadata rows written before the 7.6.5 upgrade carry text_lang = '*' (Item.ANY), because the
+-- language argument of addMetadata() was passed through verbatim. Since 7.6.5
+-- MetadataValue.setLanguage() normalizes '*' -> NULL on write, so this migration only repairs
+-- pre-existing rows; no code path can create new ones.
+--
+-- Stale '*' rows break the metadata-export -> metadata-import round trip (the export emits
+-- rejected [*] headers) and make OAI store <element name="*"/>, from which oai_openaire emits an
+-- invalid xml:lang="*".
+--
+-- Only '*' is normalized. Empty-string languages are legal and round-trip correctly - leave them.
+
+-- Step 1 must run before step 2: it uses the '*' marker to find the affected items.
+-- Bumping last_modified is what makes the reindex happen without a forced full rebuild:
+-- `dspace oai import` selects items with last_modified > watermark, and `dspace index-discovery`
+-- (no flags) reindexes documents whose search.lastindexed predates last_modified.
+UPDATE item SET last_modified = CURRENT_TIMESTAMP
+ WHERE uuid IN (SELECT dspace_object_id FROM metadatavalue WHERE text_lang = '*');
+
+-- Step 2 is deliberately not restricted to items. Rows on collections, communities and
+-- bitstreams are normalized too and need no reindex: those tables have no last_modified column,
+-- they are not in OAI or in metadata-export, and no indexing path reads the language of a
+-- non-item DSO (SolrServiceMetadataBrowseIndexingPlugin bails on non-items, and the container
+-- index factories never call getLanguage()).
+UPDATE metadatavalue SET text_lang = NULL WHERE text_lang = '*';
diff --git a/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/postgres/V7.6_2026.08.11__Normalize_metadata_language.sql b/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/postgres/V7.6_2026.08.11__Normalize_metadata_language.sql
new file mode 100644
index 00000000000..66593f23601
--- /dev/null
+++ b/dspace-api/src/main/resources/org/dspace/storage/rdbms/sqlmigration/postgres/V7.6_2026.08.11__Normalize_metadata_language.sql
@@ -0,0 +1,34 @@
+--
+-- The contents of this file are subject to the license and copyright
+-- detailed in the LICENSE and NOTICE files at the root of the source
+-- tree and available online at
+--
+-- http://www.dspace.org/license/
+--
+
+-- ufal/clarin-dspace#1406
+--
+-- Metadata rows written before the 7.6.5 upgrade carry text_lang = '*' (Item.ANY), because the
+-- language argument of addMetadata() was passed through verbatim. Since 7.6.5
+-- MetadataValue.setLanguage() normalizes '*' -> NULL on write, so this migration only repairs
+-- pre-existing rows; no code path can create new ones.
+--
+-- Stale '*' rows break the metadata-export -> metadata-import round trip (the export emits
+-- rejected [*] headers) and make OAI store <element name="*"/>, from which oai_openaire emits an
+-- invalid xml:lang="*".
+--
+-- Only '*' is normalized. Empty-string languages are legal and round-trip correctly - leave them.
+
+-- Step 1 must run before step 2: it uses the '*' marker to find the affected items.
+-- Bumping last_modified is what makes the reindex happen without a forced full rebuild:
+-- `dspace oai import` selects items with last_modified > watermark, and `dspace index-discovery`
+-- (no flags) reindexes documents whose search.lastindexed predates last_modified.
+UPDATE item SET last_modified = CURRENT_TIMESTAMP
+ WHERE uuid IN (SELECT dspace_object_id FROM metadatavalue WHERE text_lang = '*');
+
+-- Step 2 is deliberately not restricted to items. Rows on collections, communities and
+-- bitstreams are normalized too and need no reindex: those tables have no last_modified column,
+-- they are not in OAI or in metadata-export, and no indexing path reads the language of a
+-- non-item DSO (SolrServiceMetadataBrowseIndexingPlugin bails on non-items, and the container
+-- index factories never call getLanguage()).
+UPDATE metadatavalue SET text_lang = NULL WHERE text_lang = '*';