diff --git a/src/main/java/eu/dnetlib/apps/oai/OaiServerController.java b/src/main/java/eu/dnetlib/apps/oai/OaiServerController.java
index bcbb231..c37184f 100644
--- a/src/main/java/eu/dnetlib/apps/oai/OaiServerController.java
+++ b/src/main/java/eu/dnetlib/apps/oai/OaiServerController.java
@@ -1,12 +1,10 @@
 package eu.dnetlib.apps.oai;
 
 import java.io.IOException;
-import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Iterator;
-import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 
@@ -18,9 +16,11 @@ import org.dom4j.Document;
 import org.dom4j.DocumentException;
 import org.dom4j.DocumentHelper;
 import org.dom4j.Element;
-import org.dom4j.io.SAXReader;
+import org.dom4j.Namespace;
+import org.dom4j.QName;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RequestMapping;
 
 import eu.dnetlib.apps.oai.domain.OaiError;
@@ -58,6 +58,15 @@ public class OaiServerController {
 
 	}
 
+	@ExceptionHandler(Throwable.class)
+	public void handleError(final HttpServletRequest req, final HttpServletResponse response, final Exception ex) throws IOException {
+		log.error("Request: " + req.getRequestURL() + " raised " + ex.getMessage(), ex);
+
+		try (final OutputStream out = response.getOutputStream()) {
+			IOUtils.write(prepareErrorResponseXml(OaiError.badArgument), out, StandardCharsets.UTF_8);
+		}
+	}
+
 	private String oaiResponse(final Map<String, String> params) {
 		if (params == null) { return prepareErrorResponseXml(OaiError.badArgument); }
 
@@ -98,7 +107,7 @@ public class OaiServerController {
 		final Document doc = genericOaiResponse(OaiVerb.LIST_METADATA_FORMATS.getVerb());
 		final Element dataNode = doc.getRootElement().addElement(OaiVerb.LIST_METADATA_FORMATS.getVerb());
 
-		final List<OaiMetadataFormat> formats =
+		final OaiMetadataFormat[] formats =
 			StringUtils.isBlank(id) ? this.oaiService.listMetadataFormats(id) : this.oaiService.listMetadataFormats();
 
 		for (final OaiMetadataFormat oaiFormat : formats) {
@@ -260,17 +269,24 @@ public class OaiServerController {
 	}
 
 	private Document genericOaiResponse(final String verb) {
-		try (InputStream is = getClass().getResourceAsStream("/oai/oai_response.xml")) {
-			final Document doc = new SAXReader().read(is);
-			doc.selectSingleNode("//*[local-name() = 'responseDate']").setText(DateUtils.now_ISO8601());
-			doc.selectSingleNode("//*[local-name() = 'request']").setText(oaiConf.getBaseUrl());
-			if (StringUtils.isNotBlank(verb)) {
-				doc.selectSingleNode("//*[local-name() = 'request']/@verb").setText(verb);
-			}
-			return doc;
-		} catch (final DocumentException | IOException e) {
-			throw new RuntimeException("Error generataing oai response", e);
+
+		final Document doc = DocumentHelper.createDocument();
+
+		final Element root = doc.addElement("OAI-PMH", "http://www.openarchives.org/OAI/2.0/");
+
+		root.addAttribute(new QName("schemaLocation", new Namespace("xsi",
+			"http://www.w3.org/2001/XMLSchema-instance")), "http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd");
+
+		root.addElement("responseDate").setText(DateUtils.now_ISO8601());
+
+		final Element reqNode = root.addElement("request");
+		reqNode.setText(oaiConf.getBaseUrl());
+		if (StringUtils.isNotBlank(verb)) {
+			reqNode.addAttribute("verb", verb);
 		}
+
+		return doc;
+
 	}
 
 	private String prepareErrorResponseXml(final OaiError error) {
diff --git a/src/main/java/eu/dnetlib/apps/oai/OaiService.java b/src/main/java/eu/dnetlib/apps/oai/OaiService.java
index df04928..6187eb2 100644
--- a/src/main/java/eu/dnetlib/apps/oai/OaiService.java
+++ b/src/main/java/eu/dnetlib/apps/oai/OaiService.java
@@ -116,19 +116,19 @@ public class OaiService {
 
 	public OaiSet[] listSets() {
 		try {
-			return new ObjectMapper().readerForArrayOf(OaiSet.class).readValue(getClass().getResourceAsStream("oai-sets.xml"));
+			return new ObjectMapper().readerForArrayOf(OaiSet.class).readValue(getClass().getResourceAsStream("/oai-sets.json"));
 		} catch (final IOException e) {
 			throw new RuntimeException("Error obtaining oai sets");
 		}
 	}
 
-	public List<OaiMetadataFormat> listMetadataFormats(final String id) {
+	public OaiMetadataFormat[] listMetadataFormats(final String id) {
 		return listMetadataFormats();
 	}
 
-	public List<OaiMetadataFormat> listMetadataFormats() {
+	public OaiMetadataFormat[] listMetadataFormats() {
 		try {
-			return new ObjectMapper().readerForArrayOf(OaiMetadataFormat.class).readValue(getClass().getResourceAsStream("oai-metadata-formats.xml"));
+			return new ObjectMapper().readerForArrayOf(OaiMetadataFormat.class).readValue(getClass().getResourceAsStream("/oai-metadata-formats.json"));
 		} catch (final IOException e) {
 			throw new RuntimeException("Error obtaining oai sets");
 		}
@@ -165,8 +165,7 @@ public class OaiService {
 	}
 
 	private Function<String, String> prepareXsltMapper(final String metadataPrefix) {
-		return listMetadataFormats()
-			.stream()
+		return Arrays.stream(listMetadataFormats())
 			.filter(f -> f.getMetadataPrefix().equalsIgnoreCase(metadataPrefix))
 			.map(OaiMetadataFormat::getXsltPath)
 			.map(xsltPath -> this.xsltTransformerFactory.getTransformer(xsltPath, null))
diff --git a/src/main/java/eu/dnetlib/apps/oai/utils/DateUtils.java b/src/main/java/eu/dnetlib/apps/oai/utils/DateUtils.java
index 3f2310c..79f64e3 100644
--- a/src/main/java/eu/dnetlib/apps/oai/utils/DateUtils.java
+++ b/src/main/java/eu/dnetlib/apps/oai/utils/DateUtils.java
@@ -4,21 +4,16 @@ import java.time.Instant;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
-import java.util.Locale;
 import java.util.TimeZone;
 
 public class DateUtils {
 
-	private static final DateTimeFormatter DATEFORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.getDefault());
-
-	private static final DateTimeFormatter ISO8601FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ssZ", Locale.getDefault());
-
 	public static LocalDate parseDate(final String s) {
-		return LocalDate.parse(s, DATEFORMAT);
+		return LocalDate.parse(s, DateTimeFormatter.ISO_DATE);
 	}
 
 	public static String calculate_ISO8601(final LocalDateTime time) {
-		final String result = time.format(ISO8601FORMAT);
+		final String result = time.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
 		return result.substring(0, result.length() - 2) + ":" + result.substring(result.length() - 2);
 	}