diff --git a/http-core/src/main/scala/org/apache/pekko/http/scaladsl/model/HttpCharset.scala b/http-core/src/main/scala/org/apache/pekko/http/scaladsl/model/HttpCharset.scala
index 46967e1ed..c74ec3384 100644
--- a/http-core/src/main/scala/org/apache/pekko/http/scaladsl/model/HttpCharset.scala
+++ b/http-core/src/main/scala/org/apache/pekko/http/scaladsl/model/HttpCharset.scala
@@ -66,6 +66,19 @@ final case class HttpCharset private[http] (override val value: String)(val alia
   /** Returns the Charset for this charset if available or throws an exception otherwise */
   def nioCharset: Charset = _nioCharset.get
 
+  /**
+   * @return this HttpCharset instance if this charset can be parsed to a
+   * <code>java.nio.charset.Charset</code> instance, otherwise returns the UTF-8 charset.
+   * @since 1.1.0
+   */
+  def charsetWithUtf8Failover: HttpCharset = {
+    if (_nioCharset.isSuccess) {
+      this
+    } else {
+      HttpCharsets.`UTF-8`
+    }
+  }
+
   private def readObject(in: java.io.ObjectInputStream): Unit = {
     in.defaultReadObject()
     _nioCharset = HttpCharset.findNioCharset(value)
diff --git a/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/marshalling/MarshallingSpec.scala b/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/marshalling/MarshallingSpec.scala
index fe0cb7446..952b581b3 100644
--- a/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/marshalling/MarshallingSpec.scala
+++ b/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/marshalling/MarshallingSpec.scala
@@ -56,6 +56,23 @@ class MarshallingSpec extends AnyFreeSpec with Matchers with BeforeAndAfterAll w
     }
   }
 
+  "The PredefinedToEntityMarshallers" - {
+    "StringMarshaller should marshal response to `text/plain` content in UTF-8 when accept-charset is invalid" in {
+      val invalidAcceptCharsetHeader = `Accept-Charset`(HttpCharsetRange(HttpCharset.custom("invalid")))
+      val request = HttpRequest().withHeaders(invalidAcceptCharsetHeader)
+      val responseEntity = marshalToResponse("Ha“llo", request).entity
+      responseEntity.contentType.charsetOption shouldEqual Some(HttpCharsets.`UTF-8`)
+      responseEntity.contentType.mediaType shouldEqual MediaTypes.`text/plain`
+    }
+    "CharArrayMarshaller should marshal response to `text/plain` content in UTF-8 when accept-charset is invalid" in {
+      val invalidAcceptCharsetHeader = `Accept-Charset`(HttpCharsetRange(HttpCharset.custom("invalid")))
+      val request = HttpRequest().withHeaders(invalidAcceptCharsetHeader)
+      val responseEntity = marshalToResponse("Ha“llo".toCharArray(), request).entity
+      responseEntity.contentType.charsetOption shouldEqual Some(HttpCharsets.`UTF-8`)
+      responseEntity.contentType.mediaType shouldEqual MediaTypes.`text/plain`
+    }
+  }
+
   "The PredefinedToResponseMarshallers" - {
     "fromStatusCode should properly marshal a status code that doesn't allow an entity" in {
       marshalToResponse(StatusCodes.NoContent) shouldEqual HttpResponse(StatusCodes.NoContent,
diff --git a/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/server/directives/MarshallingDirectivesSpec.scala b/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/server/directives/MarshallingDirectivesSpec.scala
index 641377876..a2b2ba02c 100644
--- a/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/server/directives/MarshallingDirectivesSpec.scala
+++ b/http-tests/src/test/scala/org/apache/pekko/http/scaladsl/server/directives/MarshallingDirectivesSpec.scala
@@ -250,6 +250,11 @@ class MarshallingDirectivesSpec extends RoutingSpec with Inside {
         rejection shouldEqual UnacceptedResponseContentTypeRejection(Set(ContentType(`application/json`)))
       }
     }
+    "reject JSON rendering if an `Accept-Charset` request header requests an unknown encoding" in {
+      Get() ~> `Accept-Charset`(HttpCharset("unknown")(Nil)) ~> complete(foo) ~> check {
+        rejection shouldEqual UnacceptedResponseContentTypeRejection(Set(ContentType(`application/json`)))
+      }
+    }
     val acceptHeaderUtf = Accept.parseFromValueString("application/json;charset=utf8").right.get
     val acceptHeaderNonUtf = Accept.parseFromValueString("application/json;charset=ISO-8859-1").right.get
     "render JSON response when `Accept` header is present with the `charset` parameter ignoring it" in {
@@ -275,4 +280,43 @@ class MarshallingDirectivesSpec extends RoutingSpec with Inside {
       }
     }
   }
+
+  "The marshalling infrastructure for text" should {
+    val foo = "Hällö"
+    "render text with UTF-8 encoding if no `Accept-Charset` request header is present" in {
+      Get() ~> complete(foo) ~> check {
+        responseEntity shouldEqual HttpEntity(ContentType(`text/plain`, `UTF-8`), foo)
+      }
+    }
+    "render text with requested encoding if an `Accept-Charset` request header requests a non-UTF-8 encoding" in {
+      Get() ~> `Accept-Charset`(`ISO-8859-1`) ~> complete(foo) ~> check {
+        responseEntity shouldEqual HttpEntity(ContentType(`text/plain`, `ISO-8859-1`), foo)
+      }
+    }
+    "render text with UTF-8 encoding if an `Accept-Charset` request header requests an unknown encoding" in {
+      Get() ~> `Accept-Charset`(HttpCharset("unknown")(Nil)) ~> complete(foo) ~> check {
+        responseEntity shouldEqual HttpEntity(ContentType(`text/plain`, `UTF-8`), foo)
+      }
+    }
+  }
+
+  "The marshalling infrastructure for text/xml" should {
+    val foo = <foo>Hällö</foo>
+    "render XML with UTF-8 encoding if no `Accept-Charset` request header is present" in {
+      Get() ~> complete(foo) ~> check {
+        responseEntity shouldEqual HttpEntity(ContentType(`text/xml`, `UTF-8`), foo.toString)
+      }
+    }
+    "render XML with requested encoding if an `Accept-Charset` request header requests a non-UTF-8 encoding" in {
+      Get() ~> `Accept-Charset`(`ISO-8859-1`) ~> complete(foo) ~> check {
+        responseEntity shouldEqual HttpEntity(ContentType(`text/xml`, `ISO-8859-1`), foo.toString)
+      }
+    }
+    "render XML with UTF-8 encoding if an `Accept-Charset` request header requests an unknown encoding" ignore {
+      // still returns Content-Type: text/xml; charset=unknown
+      Get() ~> `Accept-Charset`(HttpCharset("unknown")(Nil)) ~> complete(foo) ~> check {
+        responseEntity shouldEqual HttpEntity(ContentType(`text/xml`, `UTF-8`), foo.toString)
+      }
+    }
+  }
 }
diff --git a/http/src/main/scala/org/apache/pekko/http/scaladsl/marshalling/PredefinedToEntityMarshallers.scala b/http/src/main/scala/org/apache/pekko/http/scaladsl/marshalling/PredefinedToEntityMarshallers.scala
index c4064b434..0a5ee275d 100644
--- a/http/src/main/scala/org/apache/pekko/http/scaladsl/marshalling/PredefinedToEntityMarshallers.scala
+++ b/http/src/main/scala/org/apache/pekko/http/scaladsl/marshalling/PredefinedToEntityMarshallers.scala
@@ -34,7 +34,9 @@ trait PredefinedToEntityMarshallers extends MultipartMarshallers {
   implicit val CharArrayMarshaller: ToEntityMarshaller[Array[Char]] = charArrayMarshaller(`text/plain`)
   def charArrayMarshaller(mediaType: MediaType.WithOpenCharset): ToEntityMarshaller[Array[Char]] =
     Marshaller.withOpenCharset(mediaType) { (value, charset) =>
-      marshalCharArray(value, mediaType.withCharset(charset))
+      // https://github.com/apache/pekko-http/issues/300
+      // ignore issues with invalid charset - use UTF-8 instead
+      marshalCharArray(value, mediaType.withCharset(charset.charsetWithUtf8Failover))
     }
   def charArrayMarshaller(mediaType: MediaType.WithFixedCharset): ToEntityMarshaller[Array[Char]] =
     Marshaller.withFixedContentType(mediaType) { value => marshalCharArray(value, mediaType) }
@@ -55,7 +57,11 @@ trait PredefinedToEntityMarshallers extends MultipartMarshallers {
 
   implicit val StringMarshaller: ToEntityMarshaller[String] = stringMarshaller(`text/plain`)
   def stringMarshaller(mediaType: MediaType.WithOpenCharset): ToEntityMarshaller[String] =
-    Marshaller.withOpenCharset(mediaType) { (s, cs) => HttpEntity(mediaType.withCharset(cs), s) }
+    Marshaller.withOpenCharset(mediaType) { (s, cs) =>
+      // https://github.com/apache/pekko-http/issues/300
+      // ignore issues with invalid charset - use UTF-8 instead
+      HttpEntity(mediaType.withCharset(cs.charsetWithUtf8Failover), s)
+    }
   def stringMarshaller(mediaType: MediaType.WithFixedCharset): ToEntityMarshaller[String] =
     Marshaller.withFixedContentType(mediaType) { s => HttpEntity(mediaType, s) }