diff --git a/assets/src/bundles/webapp/webapp-utils.js b/assets/src/bundles/webapp/webapp-utils.js
--- a/assets/src/bundles/webapp/webapp-utils.js
+++ b/assets/src/bundles/webapp/webapp-utils.js
@@ -360,15 +360,36 @@
   }
 }
 
+function coreSWHIDIsLowerCase(swhid) {
+  const qualifiersPos = swhid.indexOf(';');
+  let coreSWHID = swhid;
+  if (qualifiersPos !== -1) {
+    coreSWHID = swhid.slice(0, qualifiersPos);
+  }
+  return coreSWHID.toLowerCase() === coreSWHID;
+}
+
 export async function validateSWHIDInput(swhidInputElt) {
   const swhidInput = swhidInputElt.value.trim();
   let customValidity = '';
-  if (swhidInput.startsWith('swh:')) {
-    const resolveSWHIDUrl = Urls.api_1_resolve_swhid(swhidInput);
-    const response = await fetch(resolveSWHIDUrl);
-    const responseData = await response.json();
-    if (responseData.hasOwnProperty('exception')) {
-      customValidity = responseData.reason;
+  if (swhidInput.toLowerCase().startsWith('swh:')) {
+    if (coreSWHIDIsLowerCase(swhidInput)) {
+      const resolveSWHIDUrl = Urls.api_1_resolve_swhid(swhidInput);
+      const response = await fetch(resolveSWHIDUrl);
+      const responseData = await response.json();
+      if (responseData.hasOwnProperty('exception')) {
+        customValidity = responseData.reason;
+      }
+    } else {
+      const qualifiersPos = swhidInput.indexOf(';');
+      if (qualifiersPos === -1) {
+        customValidity = 'Invalid SWHID: all characters must be in lowercase. ';
+        customValidity += `Valid SWHID is ${swhidInput.toLowerCase()}`;
+      } else {
+        customValidity = 'Invalid SWHID: the core part must be in lowercase. ';
+        const coreSWHID = swhidInput.slice(0, qualifiersPos);
+        customValidity += `Valid SWHID is ${swhidInput.replace(coreSWHID, coreSWHID.toLowerCase())}`;
+      }
     }
   }
   swhidInputElt.setCustomValidity(customValidity);
diff --git a/cypress/integration/origin-search.spec.js b/cypress/integration/origin-search.spec.js
--- a/cypress/integration/origin-search.spec.js
+++ b/cypress/integration/origin-search.spec.js
@@ -511,27 +511,46 @@
       searchShouldShowNotFound(swhid, msg);
     });
 
-    function checkInvalidSWHIDReport(url, searchInputElt, repoData) {
-      const invalidSWHID = `swh:1:cnt:${repoData.content[0].sha1git};lines=45-60/`;
+    function checkInvalidSWHIDReport(url, searchInputElt, swhidInput, validationMessagePattern = '') {
       cy.visit(url);
-      doSearch(invalidSWHID, searchInputElt);
+      doSearch(swhidInput, searchInputElt);
       cy.get(searchInputElt)
         .then($el => $el[0].checkValidity()).should('be.false');
       cy.get(searchInputElt)
         .invoke('prop', 'validationMessage')
-        .should('not.equal', '');
-
+        .should('not.equal', '')
+        .should('contain', validationMessagePattern);
     }
 
     it('should report invalid SWHID in search page input', function() {
-      checkInvalidSWHIDReport(this.Urls.browse_search(), '#swh-origins-url-patterns', this.unarchivedRepo);
+      const swhidInput =
+        `swh:1:cnt:${this.unarchivedRepo.content[0].sha1git};lines=45-60/`;
+      checkInvalidSWHIDReport(this.Urls.browse_search(), '#swh-origins-url-patterns', swhidInput);
       cy.get('.invalid-feedback')
         .should('be.visible');
     });
 
     it('should report invalid SWHID in top right search input', function() {
-      checkInvalidSWHIDReport(this.Urls.browse_help(), '#swh-origins-search-top-input', this.unarchivedRepo);
+      const swhidInput =
+        `swh:1:cnt:${this.unarchivedRepo.content[0].sha1git};lines=45-60/`;
+      checkInvalidSWHIDReport(this.Urls.browse_help(), '#swh-origins-search-top-input', swhidInput);
+    });
+
+    it('should report SWHID with uppercase chars in search page input', function() {
+      const swhidInput =
+        `swh:1:cnt:${this.unarchivedRepo.content[0].sha1git}`.toUpperCase();
+      checkInvalidSWHIDReport(this.Urls.browse_search(), '#swh-origins-url-patterns', swhidInput, swhidInput.toLowerCase());
+      cy.get('.invalid-feedback')
+        .should('be.visible');
+    });
+
+    it('should report SWHID with uppercase chars in top right search input', function() {
+      let swhidInput =
+        `swh:1:cnt:${this.unarchivedRepo.content[0].sha1git}`.toUpperCase();
+      swhidInput += ';lines=45-60/';
+      checkInvalidSWHIDReport(this.Urls.browse_help(), '#swh-origins-search-top-input', swhidInput.toLowerCase());
     });
+
   });
 
 });