diff --git a/src/authInfo.ts b/src/authInfo.ts
index 28a40fa6a9..e96c233ec0 100644
--- a/src/authInfo.ts
+++ b/src/authInfo.ts
@@ -386,6 +386,35 @@ export class AuthInfo extends AsyncCreatable<AuthInfo.Options> {
     return false;
   }
 
+  /**
+   * Parse a sfdx auth url, usually obtained by `authInfo.getSfdxAuthUrl`.
+   *
+   * @example
+   * ```
+   * await AuthInfo.create(AuthInfo.parseSfdxAuthUrl(sfdxAuthUrl));
+   * ```
+   * @param sfdxAuthUrl
+   */
+  public static parseSfdxAuthUrl(sfdxAuthUrl: string) {
+    const match = sfdxAuthUrl.match(
+      /^force:\/\/([a-zA-Z0-9._-]+):([a-zA-Z0-9._-]*):([a-zA-Z0-9._-]+)@([a-zA-Z0-9._-]+)/
+    );
+
+    if (!match) {
+      throw new SfdxError(
+        'Invalid sfdx auth url. Must be in the format `force://<clientId>:<clientSecret>:<refreshToken>@<loginUrl>`. The instanceUrl must not have the protocol set.',
+        'INVALID_SFDX_AUTH_URL'
+      );
+    }
+    const [, clientId, clientSecret, refreshToken, loginUrl] = match;
+    return {
+      clientId,
+      clientSecret,
+      refreshToken,
+      loginUrl: `https://${loginUrl}`
+    };
+  }
+
   // The regular expression that filters files stored in $HOME/.sfdx
   private static authFilenameFilterRegEx: RegExp = /^[^.][^@]*@[^.]+(\.[^.\s]+)+\.json$/;
 
@@ -690,14 +719,16 @@ export class AuthInfo extends AsyncCreatable<AuthInfo.Options> {
       // Update the auth fields WITH encryption
       this.update(authConfig);
     } else {
-      const username = ensure(this.getUsername());
-      authConfig = await this.loadAuthFromConfig(username);
+      authConfig = await this.loadAuthFromConfig(ensure(this.getUsername()));
       // Update the auth fields WITHOUT encryption (already encrypted)
       this.update(authConfig, false);
     }
 
-    // Cache the fields by username (fields are encrypted)
-    AuthInfo.cache.set(ensure(this.getUsername()), this.fields);
+    const username = this.getUsername();
+    if (username) {
+      // Cache the fields by username (fields are encrypted)
+      AuthInfo.cache.set(username, this.fields);
+    }
 
     return this;
   }
diff --git a/test/unit/authInfoTest.ts b/test/unit/authInfoTest.ts
index c7f7406cde..c4e35639c1 100644
--- a/test/unit/authInfoTest.ts
+++ b/test/unit/authInfoTest.ts
@@ -611,6 +611,31 @@ describe('AuthInfo', () => {
       });
     });
 
+    it('should not cache when no username is supplied', async () => {
+      const cacheSize = AuthInfo['cache'].size;
+
+      const authResponse = {
+        access_token: testMetadata.accessToken,
+        instance_url: testMetadata.instanceUrl,
+        id: '00DAuthInfoTest_orgId/005AuthInfoTest_userId',
+        refresh_token: testMetadata.refreshToken
+      };
+
+      // Stub the http requests (OAuth2.requestToken() and the request for the username)
+      _postParmsStub.returns(Promise.resolve(authResponse));
+
+      // Create the AuthInfo instance with no username
+      await AuthInfo.create({
+        oauth2Options: {
+          refreshToken: testMetadata.refreshToken,
+          loginUrl: testMetadata.loginUrl,
+          clientId: testMetadata.clientId
+        }
+      });
+
+      expect(AuthInfo['cache'].size).to.equal(cacheSize);
+    });
+
     it('should return a JWT AuthInfo instance when passed a username from an auth file', async () => {
       const username = 'authInfoTest_username_jwt-NOT-CACHED';
 
@@ -1547,4 +1572,45 @@ describe('AuthInfo', () => {
       }
     });
   });
+
+  describe('parseSfdxAuthUrl()', () => {
+    it('should parse the correct url with no client secret', () => {
+      const options = AuthInfo.parseSfdxAuthUrl(
+        'force://PlatformCLI::5Aep861_OKMvio5gy8xCNsXxybPdupY9fVEZyeVOvb4kpOZx5Z1QLB7k7n5flEqEWKcwUQEX1I.O5DCFwjlYUB.@test.my.salesforce.com'
+      );
+
+      expect(options.refreshToken).to.equal(
+        '5Aep861_OKMvio5gy8xCNsXxybPdupY9fVEZyeVOvb4kpOZx5Z1QLB7k7n5flEqEWKcwUQEX1I.O5DCFwjlYUB.'
+      );
+      expect(options.clientId).to.equal('PlatformCLI');
+      expect(options.clientSecret).to.equal('');
+      expect(options.loginUrl).to.equal('https://test.my.salesforce.com');
+    });
+
+    it('should parse the correct url with client secret', () => {
+      const options = AuthInfo.parseSfdxAuthUrl(
+        'force://3MVG9SemV5D80oBfPBCgboxuJ9cOMLWNM1DDOZ8zgvJGsz13H3J66coUBCFF3N0zEgLYijlkqeWk4ot_Q2.4o:438437816653243682:5Aep861_OKMvio5gy8xCNsXxybPdupY9fVEZyeVOvb4kpOZx5Z1QLB7k7n5flEqEWKcwUQEX1I.O5DCFwjlYUB.@test.my.salesforce.com'
+      );
+
+      expect(options.refreshToken).to.equal(
+        '5Aep861_OKMvio5gy8xCNsXxybPdupY9fVEZyeVOvb4kpOZx5Z1QLB7k7n5flEqEWKcwUQEX1I.O5DCFwjlYUB.'
+      );
+      expect(options.clientId).to.equal(
+        '3MVG9SemV5D80oBfPBCgboxuJ9cOMLWNM1DDOZ8zgvJGsz13H3J66coUBCFF3N0zEgLYijlkqeWk4ot_Q2.4o'
+      );
+      expect(options.clientSecret).to.equal('438437816653243682');
+      expect(options.loginUrl).to.equal('https://test.my.salesforce.com');
+    });
+
+    it('should throw with incorrect url', () => {
+      try {
+        AuthInfo.parseSfdxAuthUrl(
+          'PlatformCLI::5Aep861_OKMvio5gy8xCNsXxybPdupY9fVEZyeVOvb4kpOZx5Z1QLB7k7n5flEqEWKcwUQEX1I.O5DCFwjlYUB.@test.my.salesforce.com'
+        );
+        assert.fail();
+      } catch (e) {
+        expect(e.name).to.equal('INVALID_SFDX_AUTH_URL');
+      }
+    });
+  });
 });