diff --git a/amber/src/main/scala/org/apache/texera/web/service/ExecutionsMetadataPersistService.scala b/amber/src/main/scala/org/apache/texera/web/service/ExecutionsMetadataPersistService.scala
index b9b29dff72f..bafe7a178a5 100644
--- a/amber/src/main/scala/org/apache/texera/web/service/ExecutionsMetadataPersistService.scala
+++ b/amber/src/main/scala/org/apache/texera/web/service/ExecutionsMetadataPersistService.scala
@@ -22,6 +22,7 @@ package org.apache.texera.web.service
 import com.typesafe.scalalogging.LazyLogging
 import org.apache.texera.amber.core.virtualidentity.{ExecutionIdentity, WorkflowIdentity}
 import org.apache.texera.dao.SqlServer
+import org.jooq.exception.DataAccessException
 import org.apache.texera.dao.jooq.generated.tables.daos.WorkflowExecutionsDao
 import org.apache.texera.dao.jooq.generated.tables.pojos.WorkflowExecutions
 import org.apache.texera.web.resource.dashboard.user.workflow.WorkflowVersionResource._
@@ -52,7 +53,7 @@ object ExecutionsMetadataPersistService extends LazyLogging {
 
   def insertNewExecution(
       workflowId: WorkflowIdentity,
-      uid: Option[Integer],
+      uid: Integer,
       executionName: String,
       environmentVersion: String,
       computingUnitId: Integer
@@ -64,14 +65,25 @@ object ExecutionsMetadataPersistService extends LazyLogging {
       newExecution.setName(executionName)
     }
     newExecution.setVid(vid)
-    newExecution.setUid(uid.orNull)
+    newExecution.setUid(uid)
     newExecution.setStartingTime(new Timestamp(System.currentTimeMillis()))
     newExecution.setEnvironmentVersion(environmentVersion)
 
     // Set computing unit ID if provided
     newExecution.setCuid(computingUnitId)
 
-    workflowExecutionsDao.insert(newExecution)
+    try {
+      workflowExecutionsDao.insert(newExecution)
+    } catch {
+      // A NOT NULL column (e.g. uid, vid, cuid) was null. Postgres reports this
+      // as SQLState 23502; surface a readable message instead of the raw
+      // jOOQ/JDBC stack trace, while preserving the original as the cause.
+      case e: DataAccessException if e.sqlState() == "23502" =>
+        throw new IllegalArgumentException(
+          "Cannot persist workflow execution: a required field (uid, vid, or cuid) was null.",
+          e
+        )
+    }
     ExecutionIdentity(newExecution.getEid.longValue())
   }
 
diff --git a/amber/src/main/scala/org/apache/texera/web/service/WorkflowService.scala b/amber/src/main/scala/org/apache/texera/web/service/WorkflowService.scala
index 809faf6a520..0044c959678 100644
--- a/amber/src/main/scala/org/apache/texera/web/service/WorkflowService.scala
+++ b/amber/src/main/scala/org/apache/texera/web/service/WorkflowService.scala
@@ -192,6 +192,13 @@ class WorkflowService(
 
     val (uidOpt, userEmailOpt) = userOpt.map(user => (user.getUid, user.getEmail)).unzip
 
+    // uid is NOT NULL in the DB; fail early here rather than letting the insert fail downstream.
+    val uid = uidOpt.getOrElse(
+      throw new IllegalArgumentException(
+        "Cannot start execution: a user id (uid) is required but none was provided."
+      )
+    )
+
     val workflowContext: WorkflowContext = createWorkflowContext()
     var controllerConf = ControllerConfig.default
 
@@ -204,7 +211,7 @@ class WorkflowService(
 
     workflowContext.executionId = ExecutionsMetadataPersistService.insertNewExecution(
       workflowContext.workflowId,
-      uidOpt,
+      uid,
       req.executionName,
       convertToJson(req.engineVersion),
       req.computingUnitId
diff --git a/amber/src/test/scala/org/apache/texera/web/service/ExecutionsMetadataPersistServiceSpec.scala b/amber/src/test/scala/org/apache/texera/web/service/ExecutionsMetadataPersistServiceSpec.scala
index 5c7a687728f..1d67fa03310 100644
--- a/amber/src/test/scala/org/apache/texera/web/service/ExecutionsMetadataPersistServiceSpec.scala
+++ b/amber/src/test/scala/org/apache/texera/web/service/ExecutionsMetadataPersistServiceSpec.scala
@@ -166,7 +166,7 @@ class ExecutionsMetadataPersistServiceSpec
   "insertNewExecution" should "insert a row tied to the latest workflow version" in {
     val id = ExecutionsMetadataPersistService.insertNewExecution(
       WorkflowIdentity(testWid.toLong),
-      Some(testUid),
+      testUid,
       executionName = "named-execution",
       environmentVersion = "env-1",
       computingUnitId = seededCuid
@@ -185,7 +185,7 @@ class ExecutionsMetadataPersistServiceSpec
   it should "skip setName when executionName is the empty string" in {
     val id = ExecutionsMetadataPersistService.insertNewExecution(
       WorkflowIdentity(testWid.toLong),
-      Some(testUid),
+      testUid,
       executionName = "",
       environmentVersion = "env-2",
       computingUnitId = seededCuid
@@ -198,23 +198,29 @@ class ExecutionsMetadataPersistServiceSpec
     stored.getName shouldBe "Untitled Execution"
   }
 
-  it should "throw a DB constraint violation when uid is None" in {
-    // The method signature accepts Option[Integer] for uid and calls
-    // `newExecution.setUid(uid.orNull)`, but workflow_executions.uid is
-    // NOT NULL per texera_ddl.sql, so passing None propagates a jOOQ
-    // DataAccessException. Pinning the current behavior so a future fix —
-    // either tightening the signature to a required Integer or making the
-    // column nullable — breaks the spec deliberately. See follow-up bug.
-    val ex = intercept[org.jooq.exception.DataAccessException] {
+  it should "let the DB NOT NULL constraint reject a null uid (surfaced as a readable error)" in {
+    // No more pre-insert require: a null uid is passed straight to jOOQ and the
+    // DB's NOT NULL constraint rejects it. insertNewExecution catches the
+    // resulting DataAccessException (SQLState 23502) and rethrows a readable
+    // IllegalArgumentException. Assert both the readable message and that the
+    // original DB exception is preserved as the cause, and that nothing was
+    // written.
+    val before = workflowExecutionsDao.fetchByVid(seededVid).size()
+
+    val ex = intercept[IllegalArgumentException] {
       ExecutionsMetadataPersistService.insertNewExecution(
         WorkflowIdentity(testWid.toLong),
-        None,
+        null, // uid is NOT NULL in the DB
         executionName = "anonymous",
         environmentVersion = "env-3",
         computingUnitId = seededCuid
       )
     }
     ex.getMessage should include("uid")
+    ex.getCause shouldBe a[org.jooq.exception.DataAccessException]
+
+    // The failed insert must not have persisted a row.
+    workflowExecutionsDao.fetchByVid(seededVid).size() shouldBe before
   }
 
   // -- tryGetExistingExecution ------------------------------------------------