diff --git a/lib/private/DB/MigrationService.php b/lib/private/DB/MigrationService.php
index 5e146112120..bc3168bb5a8 100644
--- a/lib/private/DB/MigrationService.php
+++ b/lib/private/DB/MigrationService.php
@@ -594,6 +594,10 @@ class MigrationService {
 				if ((!$sourceTable instanceof Table || !$sourceTable->hasColumn($thing->getName())) && $thing->getNotnull() && $thing->getType()->getName() === Types::BOOLEAN) {
 					throw new \InvalidArgumentException('Column "' . $table->getName() . '"."' . $thing->getName() . '" is type Bool and also NotNull, so it can not store "false".');
 				}
+
+				if ($thing->getLength() > 4000 && $thing->getType()->getName() === Types::STRING) {
+					throw new \InvalidArgumentException('Column "' . $table->getName() . '"."' . $thing->getName() . '" is type String, but exceeding the 4.000 length limit.');
+				}
 			}
 
 			foreach ($table->getIndexes() as $thing) {
diff --git a/tests/lib/DB/MigrationsTest.php b/tests/lib/DB/MigrationsTest.php
index b00b094b4aa..206fe1a3798 100644
--- a/tests/lib/DB/MigrationsTest.php
+++ b/tests/lib/DB/MigrationsTest.php
@@ -716,4 +716,44 @@ class MigrationsTest extends \Test\TestCase {
 
 		self::invokePrivate($this->migrationService, 'ensureOracleConstraints', [$sourceSchema, $schema, 3]);
 	}
+
+
+	public function testEnsureOracleConstraintsStringLength4000() {
+		$this->expectException(\InvalidArgumentException::class);
+
+		$column = $this->createMock(Column::class);
+		$column->expects($this->any())
+			->method('getName')
+			->willReturn('aaaa');
+		$column->expects($this->any())
+			->method('getType')
+			->willReturn(Type::getType('string'));
+		$column->expects($this->any())
+			->method('getLength')
+			->willReturn(4001);
+
+		$table = $this->createMock(Table::class);
+		$table->expects($this->any())
+			->method('getName')
+			->willReturn(\str_repeat('a', 30));
+
+		$table->expects($this->once())
+			->method('getColumns')
+			->willReturn([$column]);
+
+		$schema = $this->createMock(Schema::class);
+		$schema->expects($this->once())
+			->method('getTables')
+			->willReturn([$table]);
+
+		$sourceSchema = $this->createMock(Schema::class);
+		$sourceSchema->expects($this->any())
+			->method('getTable')
+			->willThrowException(new SchemaException());
+		$sourceSchema->expects($this->any())
+			->method('hasSequence')
+			->willReturn(false);
+
+		self::invokePrivate($this->migrationService, 'ensureOracleConstraints', [$sourceSchema, $schema, 3]);
+	}
 }