From 61d0b63208b5a8a85ca0c61d2cfaad469125e23f Mon Sep 17 00:00:00 2001
From: Houston Putman <houston@apache.org>
Date: Thu, 22 Jan 2026 12:56:22 -0800
Subject: [PATCH 1/7] Still need to fix loading a new indexWriter

---
 .../unreleased/solr-18083-fix-read-only-behavior.yml     | 9 +++++++++
 .../src/java/org/apache/solr/cloud/RecoveryStrategy.java | 5 +++--
 2 files changed, 12 insertions(+), 2 deletions(-)
 create mode 100644 changelog/unreleased/solr-18083-fix-read-only-behavior.yml

diff --git a/changelog/unreleased/solr-18083-fix-read-only-behavior.yml b/changelog/unreleased/solr-18083-fix-read-only-behavior.yml
new file mode 100644
index 000000000000..5606d08b7ac3
--- /dev/null
+++ b/changelog/unreleased/solr-18083-fix-read-only-behavior.yml
@@ -0,0 +1,9 @@
+# See https://github.com/apache/solr/blob/main/dev-docs/changelog.adoc
+title: Fix normal operation errors for readOnly collections
+type: other # added, changed, fixed, deprecated, removed, dependency_update, security, other
+authors:
+  - name: Houston Putman
+    nick: HoustonPutman
+links:
+  - name: SOLR-18083
+    url: https://issues.apache.org/jira/browse/SOLR-18083
diff --git a/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java b/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
index 0b8c2a744dab..5a774e2f6a9a 100644
--- a/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
+++ b/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
@@ -231,8 +231,9 @@ private void replicate(String nodeName, SolrCore core, ZkNodeProps leaderprops)
 
     log.info("Attempting to replicate from core [{}] on node [{}].", leaderCore, leaderBaseUrl);
 
-    // send commit if replica could be a leader
-    if (replicaType.leaderEligible) {
+    // send commit if replica could be a leader.
+    // if the collection is in readOnly mode, all replicas are already commited, so do not send a commit (which will fail because the collection cannot be written to)
+    if (replicaType.leaderEligible && !zkController.getClusterState().getCollection(coreDescriptor.getCollectionName()).isReadOnly()) {
       commitOnLeader(leaderBaseUrl, leaderCore);
     }
 

From 3f6cdf8e159cb83a4456ba5b9f0212412af103f3 Mon Sep 17 00:00:00 2001
From: Houston Putman <houston@apache.org>
Date: Fri, 23 Jan 2026 17:07:16 -0800
Subject: [PATCH 2/7] Make read only check better

---
 .../src/java/org/apache/solr/cloud/RecoveryStrategy.java   | 7 ++++---
 .../java/org/apache/solr/handler/RequestHandlerUtils.java  | 1 +
 .../java/org/apache/solr/update/CommitUpdateCommand.java   | 5 ++++-
 .../update/processor/DistributedZkUpdateProcessor.java     | 7 ++++++-
 .../java/org/apache/solr/common/params/UpdateParams.java   | 3 +++
 5 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java b/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
index 5a774e2f6a9a..9f7cb74e1fb5 100644
--- a/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
+++ b/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
@@ -231,9 +231,8 @@ private void replicate(String nodeName, SolrCore core, ZkNodeProps leaderprops)
 
     log.info("Attempting to replicate from core [{}] on node [{}].", leaderCore, leaderBaseUrl);
 
-    // send commit if replica could be a leader.
-    // if the collection is in readOnly mode, all replicas are already commited, so do not send a commit (which will fail because the collection cannot be written to)
-    if (replicaType.leaderEligible && !zkController.getClusterState().getCollection(coreDescriptor.getCollectionName()).isReadOnly()) {
+    // send commit if replica could be a leader
+    if (replicaType.leaderEligible) {
       commitOnLeader(leaderBaseUrl, leaderCore);
     }
 
@@ -304,6 +303,8 @@ private void commitOnLeader(String leaderBaseUrl, String coreName)
       // ureq.getParams().set(UpdateParams.OPEN_SEARCHER, onlyLeaderIndexes);
       // Why do we need to open searcher if "onlyLeaderIndexes"?
       ureq.getParams().set(UpdateParams.OPEN_SEARCHER, false);
+      // If the leader is readOnly, do not fail since the core is already committed.
+      ureq.getParams().set(UpdateParams.FAIL_ON_READ_ONLY, false);
       ureq.setAction(AbstractUpdateRequest.ACTION.COMMIT, false, true).process(client);
     }
   }
diff --git a/solr/core/src/java/org/apache/solr/handler/RequestHandlerUtils.java b/solr/core/src/java/org/apache/solr/handler/RequestHandlerUtils.java
index 7b5d791ae423..7a04edad33ed 100644
--- a/solr/core/src/java/org/apache/solr/handler/RequestHandlerUtils.java
+++ b/solr/core/src/java/org/apache/solr/handler/RequestHandlerUtils.java
@@ -99,6 +99,7 @@ public static void updateCommit(CommitUpdateCommand cmd, SolrParams params) {
     cmd.maxOptimizeSegments =
         params.getInt(UpdateParams.MAX_OPTIMIZE_SEGMENTS, cmd.maxOptimizeSegments);
     cmd.prepareCommit = params.getBool(UpdateParams.PREPARE_COMMIT, cmd.prepareCommit);
+    cmd.failOnReadOnly = params.getBool(UpdateParams.FAIL_ON_READ_ONLY, cmd.failOnReadOnly);
   }
 
   /**
diff --git a/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java b/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java
index 6a749af2ac91..470740583eee 100644
--- a/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java
+++ b/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java
@@ -39,6 +39,7 @@ public class CommitUpdateCommand extends UpdateCommand {
   public boolean expungeDeletes = false;
   public boolean softCommit = false;
   public boolean prepareCommit = false;
+  public boolean failOnReadOnly = true; // fail the commit if the core or collection is readOnly
 
   /**
    * User provided commit data. Can be let to null if there is none. It is possible to commit this
@@ -97,7 +98,9 @@ public String toString() {
             .append(",softCommit=")
             .append(softCommit)
             .append(",prepareCommit=")
-            .append(prepareCommit);
+            .append(prepareCommit)
+            .append(",failOnReadOnly=")
+            .append(failOnReadOnly);
     if (commitData != null) {
       sb.append(",commitData=").append(commitData);
     }
diff --git a/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java b/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
index 34532421bf56..160405f8d02f 100644
--- a/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
+++ b/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
@@ -161,7 +161,12 @@ public void processCommit(CommitUpdateCommand cmd) throws IOException {
     assert TestInjection.injectFailUpdateRequests();
 
     if (isReadOnly()) {
-      throw new SolrException(ErrorCode.FORBIDDEN, "Collection " + collection + " is read-only.");
+      if (cmd.failOnReadOnly) {
+        throw new SolrException(ErrorCode.FORBIDDEN, "Collection " + collection + " is read-only.");
+      } else {
+        // Committing on a readOnly core/collection is a no-op, since the core was committed when becoming read-only and hasn't had any updates since.
+        return;
+      }
     }
 
     List<SolrCmdDistributor.Node> nodes = null;
diff --git a/solr/solrj/src/java/org/apache/solr/common/params/UpdateParams.java b/solr/solrj/src/java/org/apache/solr/common/params/UpdateParams.java
index f14252fb9708..df6b11f1f3a3 100644
--- a/solr/solrj/src/java/org/apache/solr/common/params/UpdateParams.java
+++ b/solr/solrj/src/java/org/apache/solr/common/params/UpdateParams.java
@@ -46,6 +46,9 @@ public interface UpdateParams {
   /** expert: calls IndexWriter.prepareCommit */
   public static String PREPARE_COMMIT = "prepareCommit";
 
+  /** Fail a commit when the core or collection is in read-only mode */
+  public static String FAIL_ON_READ_ONLY = "failOnReadOnly";
+
   /** Rollback update commands */
   public static String ROLLBACK = "rollback";
 

From 5cffa98b1df59e708aac287dbbe05bb7812ad5f7 Mon Sep 17 00:00:00 2001
From: Houston Putman <houston@apache.org>
Date: Mon, 26 Jan 2026 18:04:37 -0800
Subject: [PATCH 3/7] Let some parts of solr fetch an index writer for a
 read-only core

---
 .../src/java/org/apache/solr/core/SolrCore.java    |  2 +-
 .../java/org/apache/solr/handler/IndexFetcher.java |  4 ++--
 .../apache/solr/handler/ReplicationHandler.java    |  2 +-
 .../apache/solr/update/DefaultSolrCoreState.java   |  5 +++--
 .../java/org/apache/solr/update/SolrCoreState.java | 14 +++++++++++++-
 5 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/solr/core/src/java/org/apache/solr/core/SolrCore.java b/solr/core/src/java/org/apache/solr/core/SolrCore.java
index 24c7dc83b0c9..5e246e69ff15 100644
--- a/solr/core/src/java/org/apache/solr/core/SolrCore.java
+++ b/solr/core/src/java/org/apache/solr/core/SolrCore.java
@@ -2476,7 +2476,7 @@ public RefCounted<SolrIndexSearcher> openNewSearcher(
                   true,
                   directoryFactory);
         } else {
-          RefCounted<IndexWriter> writer = getSolrCoreState().getIndexWriter(this);
+          RefCounted<IndexWriter> writer = getSolrCoreState().getIndexWriter(this, true);
           DirectoryReader newReader = null;
           try {
             newReader = indexReaderFactory.newReader(writer.get(), this);
diff --git a/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java b/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
index 704806028075..9987d93722c1 100644
--- a/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
+++ b/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
@@ -530,7 +530,7 @@ IndexFetchResult fetchLatestIndex(boolean forceReplication, boolean forceCoreRel
           // we just clear ours and commit
           log.info("New index in Leader. Deleting mine...");
           RefCounted<IndexWriter> iw =
-              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(solrCore);
+              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(solrCore, true);
           try {
             iw.get().deleteAll();
           } finally {
@@ -624,7 +624,7 @@ IndexFetchResult fetchLatestIndex(boolean forceReplication, boolean forceCoreRel
           // are successfully deleted
           solrCore.getUpdateHandler().newIndexWriter(true);
           RefCounted<IndexWriter> writer =
-              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(null);
+              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(null, true);
           try {
             IndexWriter indexWriter = writer.get();
             int c = 0;
diff --git a/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java b/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java
index cdc5de9313bb..7f50064ffe1d 100644
--- a/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java
+++ b/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java
@@ -1378,7 +1378,7 @@ public void inform(SolrCore core) {
 
           // ensure the writer is initialized so that we have a list of commit points
           RefCounted<IndexWriter> iw =
-              core.getUpdateHandler().getSolrCoreState().getIndexWriter(core);
+              core.getUpdateHandler().getSolrCoreState().getIndexWriter(core, true);
           iw.decref();
 
         } catch (IOException e) {
diff --git a/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java b/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
index 767c1ad0b77c..4feb43abd9d1 100644
--- a/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
+++ b/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
@@ -106,8 +106,9 @@ private void closeIndexWriter(IndexWriterCloser closer) {
   }
 
   @Override
-  public RefCounted<IndexWriter> getIndexWriter(SolrCore core) throws IOException {
-    if (core != null && (!core.indexEnabled || core.readOnly)) {
+  public RefCounted<IndexWriter> getIndexWriter(SolrCore core, boolean readOnlyCompatible)
+      throws IOException {
+    if (core != null && (!core.indexEnabled || (!readOnlyCompatible && core.readOnly))) {
       throw new SolrException(
           SolrException.ErrorCode.SERVICE_UNAVAILABLE, "Indexing is temporarily disabled");
     }
diff --git a/solr/core/src/java/org/apache/solr/update/SolrCoreState.java b/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
index 4d6f02d229fb..5016f9fdbb6f 100644
--- a/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
+++ b/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
@@ -178,7 +178,19 @@ public void deregisterInFlightUpdate() {
    *
    * @throws IOException If there is a low-level I/O error.
    */
-  public abstract RefCounted<IndexWriter> getIndexWriter(SolrCore core) throws IOException;
+  public RefCounted<IndexWriter> getIndexWriter(SolrCore core) throws IOException {
+    return getIndexWriter(core, false);
+  }
+
+  /**
+   * Get the current IndexWriter. If a new IndexWriter must be created, use the settings from the
+   * given {@link SolrCore}. Be very careful using the {@code readOnlyCompatible} flag, by default
+   * it should be false if the returned indexWriter will be used for writing.
+   *
+   * @throws IOException If there is a low-level I/O error.
+   */
+  public abstract RefCounted<IndexWriter> getIndexWriter(SolrCore core, boolean readOnlyCompatible)
+      throws IOException;
 
   /**
    * Rollback the current IndexWriter. When creating the new IndexWriter use the settings from the

From 42fa1da3f471aac6cecab925aa997118eda87688 Mon Sep 17 00:00:00 2001
From: Houston Putman <houston@apache.org>
Date: Mon, 26 Jan 2026 18:09:52 -0800
Subject: [PATCH 4/7] tidy and fix a small bug

---
 solr/core/src/java/org/apache/solr/handler/IndexFetcher.java   | 2 +-
 .../solr/update/processor/DistributedZkUpdateProcessor.java    | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java b/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
index 9987d93722c1..7e44992da161 100644
--- a/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
+++ b/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
@@ -537,7 +537,7 @@ IndexFetchResult fetchLatestIndex(boolean forceReplication, boolean forceCoreRel
             iw.decref();
           }
           assert TestInjection.injectDelayBeforeFollowerCommitRefresh();
-          if (skipCommitOnLeaderVersionZero) {
+          if (skipCommitOnLeaderVersionZero || solrCore.readOnly) {
             openNewSearcherAndUpdateCommitPoint();
           } else {
             SolrQueryRequest req = new LocalSolrQueryRequest(solrCore, new ModifiableSolrParams());
diff --git a/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java b/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
index 160405f8d02f..1bb785ad8b2e 100644
--- a/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
+++ b/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
@@ -164,7 +164,8 @@ public void processCommit(CommitUpdateCommand cmd) throws IOException {
       if (cmd.failOnReadOnly) {
         throw new SolrException(ErrorCode.FORBIDDEN, "Collection " + collection + " is read-only.");
       } else {
-        // Committing on a readOnly core/collection is a no-op, since the core was committed when becoming read-only and hasn't had any updates since.
+        // Committing on a readOnly core/collection is a no-op, since the core was committed when
+        // becoming read-only and hasn't had any updates since.
         return;
       }
     }

From b1cba8bec6da8c0b4748fecc526018052e48ca33 Mon Sep 17 00:00:00 2001
From: Houston Putman <houston@apache.org>
Date: Tue, 27 Jan 2026 15:23:02 -0800
Subject: [PATCH 5/7] Make some waits conditional on not being readOnly

These waits are letting updates get processed, which is not an issue for
read only collections/cores.
---
 .../apache/solr/cloud/RecoveryStrategy.java   | 20 ++++++++++---------
 .../cloud/ShardLeaderElectionContext.java     |  2 +-
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java b/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
index 9f7cb74e1fb5..bf023d3cb090 100644
--- a/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
+++ b/solr/core/src/java/org/apache/solr/cloud/RecoveryStrategy.java
@@ -659,15 +659,17 @@ public final void doSyncOrReplicateRecovery(SolrCore core) throws Exception {
           break;
         }
 
-        // we wait a bit so that any updates on the leader
-        // that started before they saw recovering state
-        // are sure to have finished (see SOLR-7141 for
-        // discussion around current value)
-        // TODO since SOLR-11216, we probably won't need this
-        try {
-          Thread.sleep(waitForUpdatesWithStaleStatePauseMilliSeconds);
-        } catch (InterruptedException e) {
-          Thread.currentThread().interrupt();
+        if (!core.readOnly) {
+          // we wait a bit so that any updates on the leader
+          // that started before they saw recovering state
+          // are sure to have finished (see SOLR-7141 for
+          // discussion around current value)
+          // TODO since SOLR-11216, we probably won't need this
+          try {
+            Thread.sleep(waitForUpdatesWithStaleStatePauseMilliSeconds);
+          } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+          }
         }
 
         // first thing we just try to sync
diff --git a/solr/core/src/java/org/apache/solr/cloud/ShardLeaderElectionContext.java b/solr/core/src/java/org/apache/solr/cloud/ShardLeaderElectionContext.java
index 16a29f89a586..96401345503b 100644
--- a/solr/core/src/java/org/apache/solr/cloud/ShardLeaderElectionContext.java
+++ b/solr/core/src/java/org/apache/solr/cloud/ShardLeaderElectionContext.java
@@ -195,7 +195,7 @@ void runLeaderProcess(boolean weAreReplacement) throws KeeperException, Interrup
         // first cancel any current recovery
         core.getUpdateHandler().getSolrCoreState().cancelRecovery();
 
-        if (weAreReplacement) {
+        if (weAreReplacement && !core.readOnly) {
           // wait a moment for any floating updates to finish
           try {
             Thread.sleep(2500);

From e6d11400004c589758d117d6d1367dbe7e4ecacf Mon Sep 17 00:00:00 2001
From: Houston Putman <houston@apache.org>
Date: Wed, 28 Jan 2026 13:53:32 -0800
Subject: [PATCH 6/7] Address some review comments

---
 changelog/unreleased/solr-18083-fix-read-only-behavior.yml | 4 ++--
 .../java/org/apache/solr/update/CommitUpdateCommand.java   | 7 ++++---
 .../solr/update/processor/DistributedUpdateProcessor.java  | 2 +-
 .../update/processor/DistributedZkUpdateProcessor.java     | 2 ++
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/changelog/unreleased/solr-18083-fix-read-only-behavior.yml b/changelog/unreleased/solr-18083-fix-read-only-behavior.yml
index 5606d08b7ac3..2aae02026c58 100644
--- a/changelog/unreleased/solr-18083-fix-read-only-behavior.yml
+++ b/changelog/unreleased/solr-18083-fix-read-only-behavior.yml
@@ -1,6 +1,6 @@
 # See https://github.com/apache/solr/blob/main/dev-docs/changelog.adoc
-title: Fix normal operation errors for readOnly collections
-type: other # added, changed, fixed, deprecated, removed, dependency_update, security, other
+title: Fix operational issues with readOnly collections, such as restarting SolrNodes and replicating from the leader.
+type: fixed # added, changed, fixed, deprecated, removed, dependency_update, security, other
 authors:
   - name: Houston Putman
     nick: HoustonPutman
diff --git a/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java b/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java
index 470740583eee..2e4d0be5fb2a 100644
--- a/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java
+++ b/solr/core/src/java/org/apache/solr/update/CommitUpdateCommand.java
@@ -98,9 +98,10 @@ public String toString() {
             .append(",softCommit=")
             .append(softCommit)
             .append(",prepareCommit=")
-            .append(prepareCommit)
-            .append(",failOnReadOnly=")
-            .append(failOnReadOnly);
+            .append(prepareCommit);
+    if (!failOnReadOnly) {
+      sb.append(",failOnReadOnly=").append(failOnReadOnly);
+    }
     if (commitData != null) {
       sb.append(",commitData=").append(commitData);
     }
diff --git a/solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java b/solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java
index 82424a5f06a4..fe6f44501e71 100644
--- a/solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java
+++ b/solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java
@@ -127,7 +127,7 @@ public static DistribPhase parseParam(final String param) {
   protected final SolrQueryResponse rsp;
   private final AtomicUpdateDocumentMerger docMerger;
 
-  private final UpdateLog ulog;
+  protected final UpdateLog ulog;
   private final VersionInfo vinfo;
   private final boolean versionsStored;
   private boolean returnVersions;
diff --git a/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java b/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
index 1bb785ad8b2e..12c2695a29d2 100644
--- a/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
+++ b/solr/core/src/java/org/apache/solr/update/processor/DistributedZkUpdateProcessor.java
@@ -166,6 +166,8 @@ public void processCommit(CommitUpdateCommand cmd) throws IOException {
       } else {
         // Committing on a readOnly core/collection is a no-op, since the core was committed when
         // becoming read-only and hasn't had any updates since.
+        assert ulog == null || !ulog.hasUncommittedChanges()
+            : "Uncommitted changes found when trying to commit on a read-only collection";
         return;
       }
     }

From 977be7bdd396eabb776c5b2b0f6c1943c18aa4ea Mon Sep 17 00:00:00 2001
From: Houston Putman <houston@apache.org>
Date: Wed, 28 Jan 2026 13:58:10 -0800
Subject: [PATCH 7/7] Change flag to failOnReadOnly

---
 solr/core/src/java/org/apache/solr/core/SolrCore.java     | 2 +-
 .../src/java/org/apache/solr/handler/IndexFetcher.java    | 4 ++--
 .../java/org/apache/solr/handler/ReplicationHandler.java  | 2 +-
 .../java/org/apache/solr/update/DefaultSolrCoreState.java | 4 ++--
 .../src/java/org/apache/solr/update/SolrCoreState.java    | 8 ++++----
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/solr/core/src/java/org/apache/solr/core/SolrCore.java b/solr/core/src/java/org/apache/solr/core/SolrCore.java
index 5e246e69ff15..4e73bd530f36 100644
--- a/solr/core/src/java/org/apache/solr/core/SolrCore.java
+++ b/solr/core/src/java/org/apache/solr/core/SolrCore.java
@@ -2476,7 +2476,7 @@ public RefCounted<SolrIndexSearcher> openNewSearcher(
                   true,
                   directoryFactory);
         } else {
-          RefCounted<IndexWriter> writer = getSolrCoreState().getIndexWriter(this, true);
+          RefCounted<IndexWriter> writer = getSolrCoreState().getIndexWriter(this, false);
           DirectoryReader newReader = null;
           try {
             newReader = indexReaderFactory.newReader(writer.get(), this);
diff --git a/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java b/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
index 7e44992da161..c9878048dbbc 100644
--- a/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
+++ b/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java
@@ -530,7 +530,7 @@ IndexFetchResult fetchLatestIndex(boolean forceReplication, boolean forceCoreRel
           // we just clear ours and commit
           log.info("New index in Leader. Deleting mine...");
           RefCounted<IndexWriter> iw =
-              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(solrCore, true);
+              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(solrCore, false);
           try {
             iw.get().deleteAll();
           } finally {
@@ -624,7 +624,7 @@ IndexFetchResult fetchLatestIndex(boolean forceReplication, boolean forceCoreRel
           // are successfully deleted
           solrCore.getUpdateHandler().newIndexWriter(true);
           RefCounted<IndexWriter> writer =
-              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(null, true);
+              solrCore.getUpdateHandler().getSolrCoreState().getIndexWriter(null, false);
           try {
             IndexWriter indexWriter = writer.get();
             int c = 0;
diff --git a/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java b/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java
index 7f50064ffe1d..e803bdd1d6b8 100644
--- a/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java
+++ b/solr/core/src/java/org/apache/solr/handler/ReplicationHandler.java
@@ -1378,7 +1378,7 @@ public void inform(SolrCore core) {
 
           // ensure the writer is initialized so that we have a list of commit points
           RefCounted<IndexWriter> iw =
-              core.getUpdateHandler().getSolrCoreState().getIndexWriter(core, true);
+              core.getUpdateHandler().getSolrCoreState().getIndexWriter(core, false);
           iw.decref();
 
         } catch (IOException e) {
diff --git a/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java b/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
index 4feb43abd9d1..e7c9474f5084 100644
--- a/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
+++ b/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
@@ -106,9 +106,9 @@ private void closeIndexWriter(IndexWriterCloser closer) {
   }
 
   @Override
-  public RefCounted<IndexWriter> getIndexWriter(SolrCore core, boolean readOnlyCompatible)
+  public RefCounted<IndexWriter> getIndexWriter(SolrCore core, boolean failOnReadOnly)
       throws IOException {
-    if (core != null && (!core.indexEnabled || (!readOnlyCompatible && core.readOnly))) {
+    if (core != null && (!core.indexEnabled || (core.readOnly && failOnReadOnly))) {
       throw new SolrException(
           SolrException.ErrorCode.SERVICE_UNAVAILABLE, "Indexing is temporarily disabled");
     }
diff --git a/solr/core/src/java/org/apache/solr/update/SolrCoreState.java b/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
index 5016f9fdbb6f..23adf63bd979 100644
--- a/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
+++ b/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
@@ -179,17 +179,17 @@ public void deregisterInFlightUpdate() {
    * @throws IOException If there is a low-level I/O error.
    */
   public RefCounted<IndexWriter> getIndexWriter(SolrCore core) throws IOException {
-    return getIndexWriter(core, false);
+    return getIndexWriter(core, true);
   }
 
   /**
    * Get the current IndexWriter. If a new IndexWriter must be created, use the settings from the
-   * given {@link SolrCore}. Be very careful using the {@code readOnlyCompatible} flag, by default
-   * it should be false if the returned indexWriter will be used for writing.
+   * given {@link SolrCore}. Be very careful using the {@code failOnReadOnly=false} flag, by default
+   * it should be true if the returned indexWriter will be used for writing.
    *
    * @throws IOException If there is a low-level I/O error.
    */
-  public abstract RefCounted<IndexWriter> getIndexWriter(SolrCore core, boolean readOnlyCompatible)
+  public abstract RefCounted<IndexWriter> getIndexWriter(SolrCore core, boolean failOnReadOnly)
       throws IOException;
 
   /**