diff --git a/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap b/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap
index b7e3d9b455..0650b13f0a 100644
--- a/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap
+++ b/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap
@@ -12,13 +12,13 @@ exports[`validation schemas PathnameSchema: for value="foo" 1`] = `"\\"value\\"
 
 exports[`validation schemas PathnameSchema: for value="https://github.com/foo" 1`] = `"\\"value\\" is not a valid pathname. Pathname should start with slash and not contain any domain or query string."`;
 
-exports[`validation schemas PluginIdSchema: for value="/docs" 1`] = `"\\"value\\" with value \\"/docs\\" fails to match the required pattern: /^[a-zA-Z_-]+$/"`;
+exports[`validation schemas PluginIdSchema: for value="/docs" 1`] = `"Illegal plugin ID value \\"/docs\\": it should only contain alphanumerics, underscores, and dashes."`;
 
-exports[`validation schemas PluginIdSchema: for value="do cs" 1`] = `"\\"value\\" with value \\"do cs\\" fails to match the required pattern: /^[a-zA-Z_-]+$/"`;
+exports[`validation schemas PluginIdSchema: for value="do cs" 1`] = `"Illegal plugin ID value \\"do cs\\": it should only contain alphanumerics, underscores, and dashes."`;
 
-exports[`validation schemas PluginIdSchema: for value="do/cs" 1`] = `"\\"value\\" with value \\"do/cs\\" fails to match the required pattern: /^[a-zA-Z_-]+$/"`;
+exports[`validation schemas PluginIdSchema: for value="do/cs" 1`] = `"Illegal plugin ID value \\"do/cs\\": it should only contain alphanumerics, underscores, and dashes."`;
 
-exports[`validation schemas PluginIdSchema: for value="docs/" 1`] = `"\\"value\\" with value \\"docs/\\" fails to match the required pattern: /^[a-zA-Z_-]+$/"`;
+exports[`validation schemas PluginIdSchema: for value="docs/" 1`] = `"Illegal plugin ID value \\"docs/\\": it should only contain alphanumerics, underscores, and dashes."`;
 
 exports[`validation schemas PluginIdSchema: for value=[] 1`] = `"\\"value\\" must be a string"`;
 
diff --git a/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts b/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts
index 29f00f7f13..5273048857 100644
--- a/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts
+++ b/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts
@@ -69,6 +69,7 @@ describe('validation schemas', () => {
     testOK('docs');
     testOK('default');
     testOK('plugin-id_with-simple-special-chars');
+    testOK('doc1');
 
     testFail('/docs');
     testFail('docs/');
diff --git a/packages/docusaurus-utils-validation/src/validationSchemas.ts b/packages/docusaurus-utils-validation/src/validationSchemas.ts
index 23e50d44c1..d89f65da80 100644
--- a/packages/docusaurus-utils-validation/src/validationSchemas.ts
+++ b/packages/docusaurus-utils-validation/src/validationSchemas.ts
@@ -11,7 +11,10 @@ import type {Tag} from '@docusaurus/utils';
 import {JoiFrontMatter} from './JoiFrontMatter';
 
 export const PluginIdSchema = Joi.string()
-  .regex(/^[a-zA-Z_-]+$/)
+  .regex(/^[a-zA-Z0-9_-]+$/)
+  .message(
+    'Illegal plugin ID value "{#value}": it should only contain alphanumerics, underscores, and dashes.',
+  )
   .default(DEFAULT_PLUGIN_ID);
 
 const MarkdownPluginsSchema = Joi.array()