diff --git a/whelktool/README.md b/whelktool/README.md
index 9312771e26..d855d278b0 100644
--- a/whelktool/README.md
+++ b/whelktool/README.md
@@ -22,20 +22,30 @@ Options
 ```
 $ java -jar build/libs/whelktool.jar --help
 usage: whelktool [options] <SCRIPT>
- -a,--allow-loud            Allow scripts to do loud modifications.
- -d,--dry-run               Do not save any modifications.
- -h,--help                  Print this help message and exit.
- -I,--skip-index            Do not index any changes, only write to
-                            storage.
- -l,--limit <LIMIT>         Amount of documents to process.
- -n,--stats-num-ids <arg>   Number of ids to print per entry in
-                            STATISTICS.txt.
- -r,--report <REPORT-DIR>   Directory where reports are written (defaults
-                            to "reports").
- -s,--step                  Change one document at a time, prompting to
-                            continue.
- -T,--no-threads            Do not use threads to parallellize batch
-                            processing.
+ -a,--allow-loud                    Allow scripts to do loud
+                                    modifications.
+ -d,--dry-run                       Do not save any modifications.
+ -h,--help                          Print this help message and exit.
+ -I,--skip-index                    Do not index any changes, only write
+                                    to storage.
+ -idchg,--allow-id-removal          [UNSAFE] Allow script to remove
+                                    document ids, e.g. sameAs.
+ -l,--limit <LIMIT>                 Amount of documents to process.
+ -n,--stats-num-ids <arg>           Number of ids to print per entry in
+                                    STATISTICS.txt.
+ -p,--parameters <PARAMETER-FILE>   Path to JSON file with parameters to
+                                    script
+ -r,--report <REPORT-DIR>           Directory where reports are written
+                                    (defaults to "reports").
+ -s,--step                          Change one document at a time,
+                                    prompting to continue.
+ -T,--no-threads                    Do not use threads to parallellize
+                                    batch processing.
+ -t,--num-threads <N>               Override default number of threads
+                                    (32).
+ -v,--validation <MODE>             [UNSAFE] Set JSON-LD validation mode.
+                                    Defaults to ON. Possible values:
+                                    ON/OFF/LOG_ONLY
 ```
 
 * Use `--dry-run` to test your script without writing any changes.
diff --git a/whelktool/src/main/groovy/whelk/datatool/WhelkTool.groovy b/whelktool/src/main/groovy/whelk/datatool/WhelkTool.groovy
index a20c32fa45..4c79d40188 100644
--- a/whelktool/src/main/groovy/whelk/datatool/WhelkTool.groovy
+++ b/whelktool/src/main/groovy/whelk/datatool/WhelkTool.groovy
@@ -1,7 +1,6 @@
 package whelk.datatool
 
 import com.google.common.util.concurrent.MoreExecutors
-import groovy.transform.Immutable
 import org.apache.logging.log4j.Logger
 import org.codehaus.groovy.jsr223.GroovyScriptEngineImpl
 import whelk.Document
@@ -9,7 +8,6 @@ import whelk.IdGenerator
 import whelk.JsonLd
 import whelk.JsonLdValidator
 import whelk.Whelk
-import whelk.datatool.form.ModifiedThing
 import whelk.datatool.form.Transform
 import whelk.datatool.util.IdLoader
 import whelk.exception.StaleUpdateException
@@ -21,12 +19,10 @@ import whelk.util.DocumentUtil
 import whelk.util.LegacyIntegrationTools
 import whelk.util.Statistics
 
-import javax.print.Doc
 import javax.script.Bindings
 import javax.script.CompiledScript
 import javax.script.ScriptEngineManager
 import javax.script.SimpleBindings
-import java.nio.charset.StandardCharsets
 import java.time.ZonedDateTime
 import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.ConcurrentLinkedQueue
@@ -41,7 +37,6 @@ import java.util.concurrent.TimeUnit
 import java.util.concurrent.atomic.AtomicInteger
 
 import static java.util.concurrent.TimeUnit.SECONDS
-import static whelk.JsonLd.RECORD_KEY
 import static whelk.util.Jackson.mapper
 
 class WhelkTool {
@@ -50,6 +45,7 @@ class WhelkTool {
     static final int DEFAULT_STATS_NUM_IDS = 3
     public static final String MAIN_LOG_NAME = "MAIN.txt"
     public static final String ERROR_LOG_NAME = "ERRORS.txt"
+    public static final String FAILED_LOG_NAME = "FAILED.txt"
     public static final String MODIFIED_LOG_NAME = "MODIFIED.txt"
     public static final String CREATED_LOG_NAME = "CREATED.txt"
     public static final String DELETED_LOG_NAME = "DELETED.txt"
@@ -68,6 +64,8 @@ class WhelkTool {
     File reportsDir
     PrintWriter mainLog
     PrintWriter errorLog
+
+    PrintWriter failedLog
     PrintWriter modifiedLog
     PrintWriter createdLog
     PrintWriter deletedLog
@@ -90,7 +88,14 @@ class WhelkTool {
 
     boolean allowLoud
     boolean allowIdRemoval
-    boolean skipValidation = false
+
+    enum ValidationMode {
+        ON,
+        OFF,
+        LOG_ONLY
+    }
+
+    ValidationMode validationMode = ValidationMode.ON
 
     Throwable errorDetected
 
@@ -123,7 +128,7 @@ class WhelkTool {
         reportsDir.mkdirs()
         mainLog = new PrintWriter(new File(reportsDir, MAIN_LOG_NAME))
         errorLog = new PrintWriter(new File(reportsDir, ERROR_LOG_NAME))
-
+        failedLog = new PrintWriter(new File(reportsDir, FAILED_LOG_NAME))
         def modifiedLogFile = new File(reportsDir, MODIFIED_LOG_NAME)
         modifiedLog = new PrintWriter(modifiedLogFile)
         def createdLogFile = new File(reportsDir, CREATED_LOG_NAME)
@@ -562,8 +567,8 @@ class WhelkTool {
         doc.setGenerationDate(new Date())
         doc.setGenerationProcess(item.generationProcess ?: script.scriptJobUri)
 
-        if (!skipValidation) {
-            validateJsonLd(doc)
+        if (validationMode in [ValidationMode.ON, ValidationMode.LOG_ONLY] && !validateJsonLd(doc)) {
+            return
         }
 
         if (recordChanges) {
@@ -582,8 +587,8 @@ class WhelkTool {
         doc.setGenerationDate(new Date())
         doc.setGenerationProcess(item.generationProcess ?: script.scriptJobUri)
 
-        if (!skipValidation) {
-            validateJsonLd(doc)
+        if (validationMode in [ValidationMode.ON, ValidationMode.LOG_ONLY] && !validateJsonLd(doc)) {
+            return
         }
 
         if (recordChanges) {
@@ -597,11 +602,19 @@ class WhelkTool {
         createdLog.println(doc.shortId)
     }
 
-    private void validateJsonLd(Document doc) {
+    private boolean validateJsonLd(Document doc) {
         List<JsonLdValidator.Error> errors = validator.validate(doc.data, doc.getLegacyCollection(whelk.jsonld))
         if (errors) {
-            throw new Exception("Invalid JSON-LD. Errors: ${errors.collect{ it.toMap() }}")
+            String msg = "Invalid JSON-LD in document ${doc.completeId}. Errors: ${errors.collect { it.toMap() }}"
+            if (validationMode == ValidationMode.ON) {
+                throw new Exception(msg)
+            } else if (validationMode == ValidationMode.LOG_ONLY) {
+                failedLog.println(doc.shortId)
+                errorLog.println(msg)
+                return true
+            }
         }
+        return false
     }
 
     private boolean confirmNextStep(String inJsonStr, Document doc) {
@@ -707,7 +720,7 @@ class WhelkTool {
         if (limit > -1) log "  limit: $limit"
         if (allowLoud) log "  allowLoud"
         if (allowIdRemoval) log "  allowIdRemoval"
-        if (skipValidation) log " skipValidation"
+        log "  validation: ${validationMode.name()}"
         log()
 
         bindings = createMainBindings()
@@ -773,7 +786,8 @@ class WhelkTool {
         cli.l(longOpt: 'limit', args: 1, argName: 'LIMIT', 'Amount of documents to process.')
         cli.a(longOpt: 'allow-loud', 'Allow scripts to do loud modifications.')
         cli.idchg(longOpt: 'allow-id-removal', '[UNSAFE] Allow script to remove document ids, e.g. sameAs.')
-        cli.sv(longOpt: 'skip-validation', '[UNSAFE] Skip JSON-LD validation before saving to database.')
+        cli.v(longOpt: 'validation', args: 1, argName: 'MODE', '[UNSAFE] Set JSON-LD validation mode. Defaults to ON.' +
+                ' Possible values: ON/OFF/LOG_ONLY')
         cli.n(longOpt: 'stats-num-ids', args: 1, 'Number of ids to print per entry in STATISTICS.txt.')
         cli.p(longOpt: 'parameters', args: 1, argName: 'PARAMETER-FILE', 'Path to JSON file with parameters to script')
 
@@ -791,9 +805,8 @@ class WhelkTool {
         try {
             script = new FileScript(scriptPath)
 
-            String paramPath = options.p
-            if (paramPath) {
-                script.setParameters(mapper.readValue(new File(paramPath).getText("UTF-8"), Map))
+            if (options.p) {
+                script.setParameters(mapper.readValue(new File(options.p).getText("UTF-8"), Map))
             }
         }
         catch (IOException e) {
@@ -806,11 +819,24 @@ class WhelkTool {
         tool.dryRun = options.d
         tool.stepWise = options.s
         tool.noThreads = options.T
-        tool.numThreads = options.t ? Integer.parseInt(options.t) : -1
-        tool.limit = options.l ? Integer.parseInt(options.l) : -1
         tool.allowLoud = options.a
         tool.allowIdRemoval = options.idchg
-        tool.skipValidation = options.sv
+        try {
+            if (options.t) {
+                tool.numThreads = Integer.parseInt(options.t)
+            }
+            if (options.l) {
+                tool.limit = Integer.parseInt(options.l)
+            }
+            if (options.v) {
+                tool.validationMode = parseValidationMode(options.v)
+            }
+        } catch (IllegalArgumentException ignored) {
+            System.err.println("Invalid argument(s)")
+            cli.usage()
+            System.exit(1)
+        }
+
         try {
             tool.run()
         } catch (Exception e) {
@@ -819,6 +845,10 @@ class WhelkTool {
         }
     }
 
+    private static ValidationMode parseValidationMode(String arg) throws IllegalArgumentException {
+        return ValidationMode.valueOf(arg.toUpperCase())
+    }
+
     void recordChange(Document before, Document after, int number) {
         //if (recordingLimit >= 0 && number > recordingLimit) {
         if (recordingLimit >= 0 && recordedChanges.size() > recordingLimit) {
diff --git a/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJob.java b/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJob.java
index 9a61712057..857fd2b330 100644
--- a/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJob.java
+++ b/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJob.java
@@ -30,8 +30,10 @@
 import static whelk.Document.HASH_IT;
 import static whelk.datatool.WhelkTool.CREATED_LOG_NAME;
 import static whelk.datatool.WhelkTool.DELETED_LOG_NAME;
+import static whelk.datatool.WhelkTool.FAILED_LOG_NAME;
 import static whelk.datatool.WhelkTool.MAIN_LOG_NAME;
 import static whelk.datatool.WhelkTool.MODIFIED_LOG_NAME;
+import static whelk.datatool.WhelkTool.ValidationMode.LOG_ONLY;
 import static whelk.datatool.bulkchange.BulkJobDocument.JOB_TYPE;
 import static whelk.datatool.bulkchange.BulkJobDocument.Status.Completed;
 import static whelk.datatool.bulkchange.BulkJobDocument.Status.Failed;
@@ -105,7 +107,8 @@ private void finish(Status status) {
                     filteredReports(),
                     lineCount(CREATED_LOG_NAME),
                     lineCount(MODIFIED_LOG_NAME),
-                    lineCount(DELETED_LOG_NAME));
+                    lineCount(DELETED_LOG_NAME),
+                    lineCount(FAILED_LOG_NAME));
         });
     }
 
@@ -163,6 +166,7 @@ protected WhelkTool buildWhelkTool(BulkJobDocument jobDoc) throws IOException {
         tool.setDefaultChangedBy(jobDoc.getChangeAgentId());
         tool.setAllowLoud(jobDoc.shouldUpdateModifiedTimestamp());
         tool.setNoThreads(false);
+        tool.setValidationMode(LOG_ONLY);
 
         return tool;
     }
diff --git a/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJobDocument.java b/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJobDocument.java
index 9ca65bdd47..b9fff29ce1 100644
--- a/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJobDocument.java
+++ b/whelktool/src/main/java/whelk/datatool/bulkchange/BulkJobDocument.java
@@ -77,6 +77,7 @@ public String key() {
     public static final String NUM_CREATED_KEY = "bulk:numCreated";
     public static final String NUM_UPDATED_KEY = "bulk:numUpdated";
     public static final String NUM_DELETED_KEY = "bulk:numDeleted";
+    public static final String NUM_FAILED_KEY = "bulk:numFailed";
 
     private static final List<Object> STATUS_PATH = List.of(JsonLd.GRAPH_KEY, 1, STATUS_KEY);
     private static final List<Object> UPDATE_TIMESTAMP_PATH = List.of(JsonLd.GRAPH_KEY, 1, SHOULD_UPDATE_TIMESTAMP_KEY);
@@ -123,7 +124,7 @@ public Map<String, Object> getSpecificationRaw() {
 
     @SuppressWarnings("unchecked")
     public void addExecution(ZonedDateTime endTime, Status status, List<String> reportPaths,
-                             long numCreated, long numUpdated, long numDeleted) {
+                             long numCreated, long numUpdated, long numDeleted, long numFailed) {
         var e = new HashMap<>(Map.of(
                 JsonLd.TYPE_KEY, EXECUTION_TYPE,
                 REPORT_KEY, reportPaths.stream().map(s -> Map.of(ID_KEY, s)).toList(),
@@ -140,6 +141,9 @@ public void addExecution(ZonedDateTime endTime, Status status, List<String> repo
         if (numDeleted > 0) {
             e.put(NUM_DELETED_KEY, numDeleted);
         }
+        if (numFailed > 0) {
+            e.put(NUM_FAILED_KEY, numFailed);
+        }
 
         var executions = asList(get(data, EXECUTION_PATH));
         executions.add(e);
diff --git a/whelktool/src/main/java/whelk/datatool/bulkchange/BulkPreviewJob.java b/whelktool/src/main/java/whelk/datatool/bulkchange/BulkPreviewJob.java
index 1b61807c7d..2a501eaaaa 100644
--- a/whelktool/src/main/java/whelk/datatool/bulkchange/BulkPreviewJob.java
+++ b/whelktool/src/main/java/whelk/datatool/bulkchange/BulkPreviewJob.java
@@ -11,6 +11,7 @@
 import java.nio.file.Files;
 import java.util.List;
 
+import static whelk.datatool.WhelkTool.ValidationMode.LOG_ONLY;
 import static whelk.datatool.bulkchange.BulkJobDocument.JOB_TYPE;
 
 public class BulkPreviewJob extends BulkJob {
@@ -30,6 +31,7 @@ public BulkPreviewJob(Whelk whelk, String id) throws IOException {
         tool.setDryRun(true);
         tool.setRecordChanges(true);
         tool.setRecordingLimit(RECORD_MAX_ITEMS);
+        tool.setValidationMode(LOG_ONLY);
         tool.setLogger(log);
     }