diff --git a/_locales/en/messages.json b/_locales/en/messages.json
index 2e5e9b971..d7b79e930 100644
--- a/_locales/en/messages.json
+++ b/_locales/en/messages.json
@@ -2532,5 +2532,11 @@
   },
   "devicesSettingsDescription": {
     "message": "Managed linked devices"
+  },
+  "mnemonicEmpty": {
+    "message": "Seed is mandatory"
+  },
+  "displayNameEmpty": {
+    "message": "Display Name Is Mandatory"
   }
 }
diff --git a/stylesheets/_session.scss b/stylesheets/_session.scss
index 9fa3c5429..6c4aafce0 100644
--- a/stylesheets/_session.scss
+++ b/stylesheets/_session.scss
@@ -222,8 +222,6 @@ $session_message-container-border-radius: 5px;
     border: 2px solid $textAndBorderColor;
   }
 
-  
-
   width: auto;
   border: none;
   display: flex;
@@ -246,8 +244,7 @@ $session_message-container-border-radius: 5px;
       border: 2px solid $session-color-green;
       background-color: $session-color-green;
 
-      &.disabled,
-      &:disabled {
+      &.disabled {
         background-color: rgba($session-color-green, 0.6);
       }
     }
@@ -294,7 +291,6 @@ $session_message-container-border-radius: 5px;
   &.square-outline {
     &.green {
       @include transparent-background($session-color-green);
-
     }
     &.white {
       @include transparent-background($session-color-white);
@@ -338,7 +334,6 @@ $session_message-container-border-radius: 5px;
   &.square-outline {
     border-radius: 0px;
   }
-  
 
   &:hover {
     filter: brightness(80%);
@@ -520,64 +515,6 @@ label {
   cursor: pointer;
 }
 
-.input-with-label-container {
-  height: 46.5px;
-  width: 280px;
-  color: $session-color-white;
-  padding: 2px 0 2px 0;
-  transition: opacity $session-transition-duration;
-  opacity: 1;
-  position: relative;
-
-  label {
-    line-height: 14px;
-    opacity: 0;
-    color: #737373;
-    font-size: 10px;
-    line-height: 11px;
-    position: absolute;
-    top: 0px;
-  }
-
-  &.filled {
-    opacity: 1;
-  }
-
-  input {
-    border: none;
-    outline: 0;
-    height: 14px;
-    width: 280px;
-    background: transparent;
-    color: $session-color-white;
-    font-size: 12px;
-    line-height: 14px;
-    position: absolute;
-    top: 50%;
-    transform: translateY(-50%);
-  }
-
-  hr {
-    border: 1px solid $session-color-white;
-    width: 100%;
-    position: absolute;
-    bottom: 0px;
-  }
-
-  button {
-    position: absolute;
-    top: 50%;
-    transform: translateY(-50%);
-    right: 0px;
-  }
-}
-
-.user-details-dialog {
-  .message {
-    word-break: break-all;
-  }
-}
-
 #session-toast-container {
   position: fixed;
   right: $session-margin-lg;
diff --git a/stylesheets/_session_signin.scss b/stylesheets/_session_signin.scss
index 2e4a573cd..1b067d71e 100644
--- a/stylesheets/_session_signin.scss
+++ b/stylesheets/_session_signin.scss
@@ -62,7 +62,6 @@
 
     &__content {
       width: 100%;
-      overflow-y: auto;
       padding-top: 20px;
     }
 
@@ -112,10 +111,11 @@
 
     &__welcome-session {
       @include registration-label-mixin;
-      font-size: 12px;
+      font-size: 14px;
       font-weight: 700;
-      line-height: 12px;
+      line-height: 14px;
       padding-top: 2em;
+      text-align: center;
     }
 
     &__unique-session-id {
@@ -157,6 +157,10 @@
       opacity: 1;
     }
 
+    &.error {
+      color: red;
+    }
+
     input {
       border: none;
       outline: 0;
diff --git a/ts/components/session/RegistrationTabs.tsx b/ts/components/session/RegistrationTabs.tsx
index 64d68486d..fed62801b 100644
--- a/ts/components/session/RegistrationTabs.tsx
+++ b/ts/components/session/RegistrationTabs.tsx
@@ -40,6 +40,8 @@ interface State {
   mnemonicSeed: string;
   hexGeneratedPubKey: string;
   primaryDevicePubKey: string;
+  mnemonicError: string | undefined;
+  displayNameError: string | undefined;
 }
 
 const Tab = ({
@@ -111,6 +113,8 @@ export class RegistrationTabs extends React.Component<{}, State> {
       mnemonicSeed: '',
       hexGeneratedPubKey: '',
       primaryDevicePubKey: '',
+      mnemonicError: undefined,
+      displayNameError: undefined,
     };
 
     this.accountManager = window.getAccountManager();
@@ -196,25 +200,39 @@ export class RegistrationTabs extends React.Component<{}, State> {
       mnemonicSeed: '',
       hexGeneratedPubKey: '',
       primaryDevicePubKey: '',
+      mnemonicError: undefined,
+      displayNameError: undefined,
     });
   };
 
   private onSeedChanged(val: string) {
-    this.setState({ mnemonicSeed: val });
+    this.setState({
+      mnemonicSeed: val,
+      mnemonicError: !val ? window.i18n('mnemonicEmpty') : undefined,
+    });
   }
 
   private onDisplayNameChanged(val: string) {
     const sanitizedName = this.sanitiseNameInput(val);
-    this.setState({ displayName: sanitizedName });
+    this.setState({
+      displayName: sanitizedName,
+      displayNameError: !sanitizedName
+        ? window.i18n('displayNameEmpty')
+        : undefined,
+    });
   }
 
   private onPasswordChanged(val: string) {
-    this.setState({ password: val });
-    this.onValidatePassword(); // FIXME add bubbles or something to help the user know what he did wrong
+    this.setState({ password: val }, () => {
+      this.validatePassword();
+    });
   }
 
   private onPasswordVerifyChanged(val: string) {
     this.setState({ validatePassword: val });
+    this.setState({ validatePassword: val }, () => {
+      this.validatePassword();
+    });
   }
 
   private renderSections() {
@@ -250,6 +268,21 @@ export class RegistrationTabs extends React.Component<{}, State> {
         );
 
       default:
+        const {
+          passwordErrorString,
+          passwordFieldsMatch,
+          displayNameError,
+          displayName,
+          password,
+        } = this.state;
+
+        let enableCompleteSignUp = true;
+        const displayNameOK = !displayNameError && !!displayName; //display name required
+        const passwordsOK =
+          !password || (!passwordErrorString && passwordFieldsMatch); // password is valid if empty, or if no error and fields are matching
+
+        enableCompleteSignUp = displayNameOK && passwordsOK;
+
         return (
           <div className="session-registration__content">
             <div className="session-registration__welcome-session">
@@ -264,6 +297,7 @@ export class RegistrationTabs extends React.Component<{}, State> {
               buttonType={SessionButtonType.Brand}
               buttonColor={SessionButtonColor.Green}
               text={window.i18n('completeSignUp')}
+              enabled={enableCompleteSignUp}
             />
           </div>
         );
@@ -399,6 +433,11 @@ export class RegistrationTabs extends React.Component<{}, State> {
   }
 
   private renderNamePasswordAndVerifyPasswordFields() {
+    const passwordDoesNotMatchString =
+      !this.state.passwordFieldsMatch && this.state.password
+        ? window.i18n('passwordsDoNotMatch')
+        : undefined;
+
     return (
       <div className="inputfields">
         <SessionInput
@@ -416,6 +455,7 @@ export class RegistrationTabs extends React.Component<{}, State> {
 
         <SessionInput
           label={window.i18n('optionalPassword')}
+          error={this.state.passwordErrorString}
           type="password"
           placeholder={window.i18n('enterOptionalPassword')}
           onValueChanged={(val: string) => {
@@ -428,6 +468,7 @@ export class RegistrationTabs extends React.Component<{}, State> {
 
         <SessionInput
           label={window.i18n('verifyPassword')}
+          error={passwordDoesNotMatchString}
           type="password"
           placeholder={window.i18n('optionalPassword')}
           onValueChanged={(val: string) => {
@@ -488,7 +529,7 @@ export class RegistrationTabs extends React.Component<{}, State> {
           <h4>{or}</h4>
           {this.renderRestoreUsingSeedButton(
             SessionButtonType.BrandOutline,
-            SessionButtonColor.Green
+            SessionButtonColor.White
           )}
         </div>
       );
@@ -525,6 +566,32 @@ export class RegistrationTabs extends React.Component<{}, State> {
   }
 
   private renderContinueYourSessionButton() {
+    const {
+      signUpMode,
+      signInMode,
+      passwordErrorString,
+      passwordFieldsMatch,
+      displayNameError,
+      mnemonicError,
+      primaryDevicePubKey,
+      displayName,
+      mnemonicSeed,
+      password,
+    } = this.state;
+
+    let enableContinue = true;
+    const displayNameOK = !displayNameError && !!displayName; //display name required
+    const mnemonicOK = !mnemonicError && !!mnemonicSeed; //Mnemonic required
+    const passwordsOK =
+      !password || (!passwordErrorString && passwordFieldsMatch); // password is valid if empty, or if no error and fields are matching
+    if (signInMode === SignInMode.UsingSeed) {
+      enableContinue = displayNameOK && mnemonicOK && passwordsOK;
+    } else if (signInMode === SignInMode.LinkingDevice) {
+      enableContinue = !!primaryDevicePubKey;
+    } else if (signUpMode === SignUpMode.EnterDetails) {
+      enableContinue = displayNameOK && passwordsOK;
+    }
+
     return (
       <SessionButton
         onClick={() => {
@@ -533,6 +600,7 @@ export class RegistrationTabs extends React.Component<{}, State> {
         buttonType={SessionButtonType.Brand}
         buttonColor={SessionButtonColor.Green}
         text={window.i18n('continueYourSession')}
+        enabled={enableContinue}
       />
     );
   }
@@ -603,37 +671,37 @@ export class RegistrationTabs extends React.Component<{}, State> {
 
     // If user hasn't set a value then skip
     if (!input && !confirmationInput) {
-      return null;
+      this.setState({
+        passwordErrorString: '',
+        passwordFieldsMatch: true,
+      });
+
+      return;
     }
 
     const error = window.passwordUtil.validatePassword(input, window.i18n);
     if (error) {
-      return error;
-    }
+      this.setState({
+        passwordErrorString: error,
+        passwordFieldsMatch: true,
+      });
 
-    if (input !== confirmationInput) {
-      return "Password don't match";
+      return;
     }
 
-    return null;
-  }
-
-  private onValidatePassword() {
-    const passwordValidation = this.validatePassword();
-    if (passwordValidation) {
-      this.setState({ passwordErrorString: passwordValidation });
-    } else {
-      // Show green box around inputs that match
-      const input = this.trim(this.state.password);
-      const confirmationInput = this.trim(this.state.validatePassword);
-      const passwordFieldsMatch =
-        input !== undefined && input === confirmationInput;
-
+    if (input !== confirmationInput) {
       this.setState({
         passwordErrorString: '',
-        passwordFieldsMatch,
+        passwordFieldsMatch: false,
       });
+
+      return;
     }
+
+    this.setState({
+      passwordErrorString: '',
+      passwordFieldsMatch: true,
+    });
   }
 
   private sanitiseNameInput(val: string) {
@@ -654,10 +722,21 @@ export class RegistrationTabs extends React.Component<{}, State> {
   }
 
   private async register(language: string) {
-    const { password, mnemonicSeed, displayName } = this.state;
+    const {
+      password,
+      mnemonicSeed,
+      displayName,
+      passwordErrorString,
+      passwordFieldsMatch,
+    } = this.state;
     // Make sure the password is valid
-    if (this.validatePassword()) {
-      //this.showToast(window.i18n('invalidPassword'));
+    if (passwordErrorString || passwordFieldsMatch) {
+      window.pushToast({
+        title: window.i18n('invalidPassword'),
+        type: 'success',
+        id: 'invalidPassword',
+      });
+
       return;
     }
     if (!mnemonicSeed) {
diff --git a/ts/components/session/SessionButton.tsx b/ts/components/session/SessionButton.tsx
index 9b51f4091..7dc4c2a24 100644
--- a/ts/components/session/SessionButton.tsx
+++ b/ts/components/session/SessionButton.tsx
@@ -28,6 +28,7 @@ interface Props {
   buttonType: SessionButtonType;
   buttonColor: SessionButtonColor;
   onClick: any;
+  enabled?: boolean;
 }
 
 export class SessionButton extends React.PureComponent<Props> {
diff --git a/ts/components/session/SessionInput.tsx b/ts/components/session/SessionInput.tsx
index b4789ae9a..5c74762c5 100644
--- a/ts/components/session/SessionInput.tsx
+++ b/ts/components/session/SessionInput.tsx
@@ -5,6 +5,7 @@ import { SessionIconButton, SessionIconSize, SessionIconType } from './icon';
 
 interface Props {
   label: string;
+  error?: string;
   type: string;
   value?: string;
   placeholder: string;
@@ -32,23 +33,14 @@ export class SessionInput extends React.PureComponent<Props, State> {
   }
 
   public render() {
-    const { placeholder, type, label, value, enableShowHide } = this.props;
-    const { inputValue, forceShow } = this.state;
+    const { placeholder, type, value, enableShowHide, error } = this.props;
+    const { forceShow } = this.state;
 
     const correctType = forceShow ? 'text' : type;
 
     return (
       <div className="session-input-with-label-container">
-        <label
-          htmlFor="session-input-floating-label"
-          className={classNames(
-            inputValue !== ''
-              ? 'session-input-with-label-container filled'
-              : 'session-input-with-label-container'
-          )}
-        >
-          {label}
-        </label>
+        {error ? this.renderError() : this.renderLabel()}
         <input
           id="session-input-floating-label"
           type={correctType}
@@ -75,6 +67,39 @@ export class SessionInput extends React.PureComponent<Props, State> {
     );
   }
 
+  private renderLabel() {
+    const { inputValue } = this.state;
+    const { label } = this.props;
+
+    return (
+      <label
+        htmlFor="session-input-floating-label"
+        className={classNames(
+          inputValue !== ''
+            ? 'session-input-with-label-container filled'
+            : 'session-input-with-label-container'
+        )}
+      >
+        {label}
+      </label>
+    );
+  }
+
+  private renderError() {
+    const { error } = this.props;
+
+    return (
+      <label
+        htmlFor="session-input-floating-label"
+        className={classNames(
+          'session-input-with-label-container filled error'
+        )}
+      >
+        {error}
+      </label>
+    );
+  }
+
   private renderShowHideButton() {
     return (
       <SessionIconButton