Fix Elasticsearch Index Readonly

What's Actually Happening

Your Elasticsearch index is in readonly mode, preventing all write operations. Documents cannot be indexed, updated, or deleted.

The Error You'll See

```bash $ curl -XPOST 'localhost:9200/myindex/_doc' -d '{"test":"data"}'

{ "error": { "type": "index_read_only_exception", "reason": "index read-only / allow delete (api)" } } ```

Why This Happens

1. 1.Disk flood stage - Disk usage > 95%
2. 2.Flood stage triggered - Automatic protection activated
3. 3.Manual setting - Index set to readonly
4. 4.Allocation failed - Shard cannot be allocated

Step 1: Check Index Settings

```bash # Check index settings: curl -XGET 'localhost:9200/myindex/_settings?pretty'

# Check readonly flag: curl -XGET 'localhost:9200/myindex/_settings?pretty' | grep read_only ```

Step 2: Check Disk Space

```bash # Check disk usage: curl -XGET 'localhost:9200/_cat/allocation?v'

# Check flood stage watermark: curl -XGET 'localhost:9200/_cluster/settings?pretty' | grep flood ```

Step 3: Clear Readonly Flag

```bash # Clear readonly for specific index: curl -XPUT 'localhost:9200/myindex/_settings' -d '{ "index.blocks.read_only_allow_delete": null }'

# Clear for all indices: curl -XPUT 'localhost:9200/_all/_settings' -d '{ "index.blocks.read_only_allow_delete": null }' ```

Elasticsearch Index Readonly Checklist

Verify the Fix

```bash # Test write: curl -XPOST 'localhost:9200/myindex/_doc' -d '{"test":"data"}' # Output: created: true

# Check settings: curl -XGET 'localhost:9200/myindex/_settings?pretty' | grep read_only # Output: No readonly setting ```

Related Issues

• [Fix Elasticsearch Cluster Red Status](/articles/fix-elasticsearch-cluster-red-status)
• [Fix Elasticsearch Shard Allocation Failed](/articles/fix-elasticsearch-shard-allocation-failed)