diff --git a/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/IidmVersion.java b/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/IidmVersion.java
index 2ae095c49ab..91ebf553128 100644
--- a/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/IidmVersion.java
+++ b/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/IidmVersion.java
@@ -14,8 +14,7 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import static com.powsybl.iidm.serde.IidmSerDeConstants.ITESLA_DOMAIN;
-import static com.powsybl.iidm.serde.IidmSerDeConstants.POWSYBL_DOMAIN;
+import static com.powsybl.iidm.serde.IidmSerDeConstants.*;
 
 /**
  * @author Miora Ralambotiana {@literal <miora.ralambotiana at rte-france.com>}
@@ -83,6 +82,15 @@ public String getXsd(boolean valid) {
         return "iidm_equipment_V" + toString("_") + ".xsd";
     }
 
+    public static IidmVersion of(String version, String separator) {
+        Objects.requireNonNull(version);
+        return Stream.of(IidmVersion.values())
+                .filter(v -> version.equals(v.toString(separator)))
+                .findFirst() // there can only be 0 or exactly 1 match
+                .orElseThrow(() -> new PowsyblException("IIDM Version " + version + " is not supported. Max supported version: "
+                        + CURRENT_IIDM_VERSION.toString(separator)));
+    }
+
     public static IidmVersion fromNamespaceURI(String namespaceURI) {
         String version = namespaceURI.substring(namespaceURI.lastIndexOf('/') + 1);
         IidmVersion v = of(version, "_");
@@ -97,11 +105,4 @@ public static IidmVersion fromNamespaceURI(String namespaceURI) {
         return v;
     }
 
-    public static IidmVersion of(String version, String separator) {
-        Objects.requireNonNull(version);
-        return Stream.of(IidmVersion.values())
-                .filter(v -> version.equals(v.toString(separator)))
-                .findFirst() // there can only be 0 or exactly 1 match
-                .orElseThrow(() -> new PowsyblException("Version " + version + " is not supported."));
-    }
 }
diff --git a/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/XMLImporter.java b/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/XMLImporter.java
index 9d954ba1105..face054753d 100644
--- a/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/XMLImporter.java
+++ b/iidm/iidm-serde/src/main/java/com/powsybl/iidm/serde/XMLImporter.java
@@ -58,32 +58,73 @@ public String getComment() {
     }
 
     protected boolean exists(ReadOnlyDataSource dataSource, String ext) throws IOException {
-        try {
-            if (ext != null) {
-                try (InputStream is = dataSource.newInputStream(null, ext)) {
-                    // check the first root element is network and namespace is IIDM
-                    XMLStreamReader xmlsr = getXMLInputFactory().createXMLStreamReader(is);
-                    try {
-                        while (xmlsr.hasNext()) {
-                            int eventType = xmlsr.next();
-                            if (eventType == XMLStreamConstants.START_ELEMENT) {
-                                String name = xmlsr.getLocalName();
-                                String ns = xmlsr.getNamespaceURI();
-                                return NetworkSerDe.NETWORK_ROOT_ELEMENT_NAME.equals(name)
-                                        && (Stream.of(IidmVersion.values()).anyMatch(v -> v.getNamespaceURI().equals(ns))
-                                        || Stream.of(IidmVersion.values()).filter(v -> v.compareTo(IidmVersion.V_1_7) >= 0).anyMatch(v -> v.getNamespaceURI(false).equals(ns)));
-                            }
-                        }
-                    } finally {
-                        cleanClose(xmlsr);
+        if (ext == null) {
+            return false;
+        }
+
+        try (InputStream is = dataSource.newInputStream(null, ext)) {
+            XMLStreamReader xmlsr = getXMLInputFactory().createXMLStreamReader(is);
+            try {
+                return isValidNetworkRoot(xmlsr);
+            } finally {
+                cleanClose(xmlsr);
+            }
+        } catch (XMLStreamException e) {
+            return false; // not a valid XML file
+        }
+    }
+
+    private boolean isValidNetworkRoot(XMLStreamReader xmlsr) throws XMLStreamException {
+        while (xmlsr.hasNext()) {
+            if (xmlsr.next() == XMLStreamConstants.START_ELEMENT) {
+                String name = xmlsr.getLocalName();
+                String ns = xmlsr.getNamespaceURI();
+
+                if (!NetworkSerDe.NETWORK_ROOT_ELEMENT_NAME.equals(name) || ns.isEmpty()) {
+                    return false;
+                }
+
+                String currentPrefix = extractPrefix(ns);
+                if (isValidPrefix(currentPrefix)) {
+                    String version = extractVersion(ns);
+                    if (!version.isEmpty()) {
+                        // If it is not supported, this will throw an exception giving details on the encountered version
+                        // and the maximum supported version.
+                        IidmVersion.of(version, "_");
+                        return isValidNamespace(ns);
                     }
                 }
             }
-            return false;
-        } catch (XMLStreamException e) {
-            // not a valid xml file
-            return false;
         }
+        return false;
+    }
+
+    private String extractPrefix(String namespace) {
+        int lastSlash = namespace.lastIndexOf('/');
+        return (lastSlash > 0) ? namespace.substring(0, lastSlash) : namespace;
+    }
+
+    private String extractVersion(String namespace) {
+        int lastSlash = namespace.lastIndexOf('/');
+        return (lastSlash >= 0 && lastSlash < namespace.length() - 1) ? namespace.substring(lastSlash + 1) : "";
+    }
+
+    private boolean isValidPrefix(String prefix) {
+        return Stream.of(IidmVersion.values())
+                .map(v -> extractPrefix(v.getNamespaceURI(true)))
+                .anyMatch(prefix::equals)
+                || Stream.of(IidmVersion.values())
+                .filter(v -> v.compareTo(IidmVersion.V_1_7) >= 0)
+                .map(v -> extractPrefix(v.getNamespaceURI(false)))
+                .anyMatch(prefix::equals);
+    }
+
+    private boolean isValidNamespace(String ns) {
+        return Stream.of(IidmVersion.values())
+                .anyMatch(v -> v.getNamespaceURI().equals(ns))
+                || Stream.of(IidmVersion.values())
+                .filter(v -> v.compareTo(IidmVersion.V_1_7) >= 0)
+                .anyMatch(v -> v.getNamespaceURI(false).equals(ns));
     }
 
     private void cleanClose(XMLStreamReader xmlStreamReader) {
diff --git a/iidm/iidm-serde/src/test/java/com/powsybl/iidm/serde/XMLImporterTest.java b/iidm/iidm-serde/src/test/java/com/powsybl/iidm/serde/XMLImporterTest.java
index 850f42aa4f5..e9e74a31fea 100644
--- a/iidm/iidm-serde/src/test/java/com/powsybl/iidm/serde/XMLImporterTest.java
+++ b/iidm/iidm-serde/src/test/java/com/powsybl/iidm/serde/XMLImporterTest.java
@@ -8,6 +8,7 @@
 package com.powsybl.iidm.serde;
 
 import com.google.common.io.ByteStreams;
+import com.powsybl.commons.PowsyblException;
 import com.powsybl.commons.datasource.*;
 import com.powsybl.commons.report.PowsyblCoreReportResourceBundle;
 import com.powsybl.commons.test.PowsyblTestReportResourceBundle;
@@ -23,6 +24,7 @@
 import java.io.StringWriter;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Properties;
@@ -90,6 +92,22 @@ private void writeNetworkWithComment(String fileName) throws IOException {
         }
     }
 
+    private void writeNetworkUnsupportedIidmVersion(String fileName) throws IOException {
+        writeNetwork(fileName, unsupportedIidmVersionNamespaceURI(), false);
+    }
+
+    private static String unsupportedIidmVersion() {
+        String[] currentIidmVersionSplit = CURRENT_IIDM_VERSION.toString().split("_");
+        int unsupportedIidmVersionMajor = Integer.parseInt(currentIidmVersionSplit[1]);
+        int unsupportedIidmVersionMinor = Integer.parseInt(currentIidmVersionSplit[2]) + 1;
+        return String.format("%d.%d", unsupportedIidmVersionMajor, unsupportedIidmVersionMinor);
+    }
+
+    private String unsupportedIidmVersionNamespaceURI() {
+        String currentIidmNamespaceURI = CURRENT_IIDM_VERSION.getNamespaceURI();
+        return currentIidmNamespaceURI.substring(0, currentIidmNamespaceURI.lastIndexOf("/") + 1) + unsupportedIidmVersion();
+    }
+
     @BeforeEach
     public void setUp() throws IOException {
         super.setUp();
@@ -116,6 +134,7 @@ public void setUp() throws IOException {
         }
         writeNetworkWithComment("/test7.xiidm");
         writeNetworkWithExtension("/test8.xiidm", CURRENT_IIDM_VERSION.getNamespaceURI());
+        writeNetworkUnsupportedIidmVersion("/test9.xiidm");
 
         importer = new XMLImporter();
     }
@@ -154,6 +173,15 @@ void exists() {
         assertFalse(importer.exists(new DirectoryDataSource(fileSystem.getPath("/"), "testDummy"))); // namespace URI is not defined
     }
 
+    @Test
+    void testUnsupportedIidmVersion() {
+        Path dir = fileSystem.getPath("/");
+        ReadOnlyDataSource dataSource = new DirectoryDataSource(dir, "test9");
+        String expectedError = "IIDM Version " + unsupportedIidmVersion() + "is not supported. Max supported version: "
+                + CURRENT_IIDM_VERSION.toString(".");
+        assertThrows(PowsyblException.class, () -> importer.exists(dataSource), expectedError);
+    }
+
     @Test
     void copy() throws Exception {
         importer.copy(new DirectoryDataSource(fileSystem.getPath("/"), "test0"), new DirectoryDataSource(fileSystem.getPath("/"), "test0_copy"));