Ok, let me fully break down what I have right now. I followed the instructions and made the changes mentioned above. Also created a snippet called avatarUpload with the code mentioned above.
My update profile looks like this:
[[!UpdateProfile? &useExtended=`1`
&postHooks=`postHook.DiscussUpdateProfile`,`redirect_profile_update`
&preHooks=`user_profile_image`,`user_profile_image`]]
[[!DiscussUpdateProfileLoader]]
<div class="prof-update">
<div class="update-profile">
<div class="updprof-error">
[[+error.message]]
</div>
[[+login.update_success:if=`[[+login.update_success]]`:is=`1`:then=`[[%login.profile_updated? &namespace=`login` &topic=`updateprofile`]]`]]
<form class="form" enctype="multipart/form-data" action="[[~[[*id]]]]" method="post">
<input type="hidden" name="nospam:blank" value="" />
<p>
<label for="fullname">[[!%login.fullname? &namespace=`login` &topic=`updateprofile`]]
<span class="error">[[+error.fullname]]</span>
</label>
<br />
<input type="text" name="fullname" id="fullname" value="[[+fullname]]" />
</p>
<p>
<label for="email">[[!%login.email]]
<span class="error">[[+error.email]]</span>
</label>
<br />
<input type="text" name="email:required:email" id="email" value="[[+email]]" />
</p>
<p>
<label for="gender">Gender
<span class="error">[[+error.gender]]</span>
</label>
<br />
<select name="gender">
<option value="m" [[+gender::is=`m`:then=`selected`]]>Male</option>
<option value="f" [[+gender:is=`f`:then=`selected`]]>Female</option>
</select>
</p>
<p>
<label for="country">[[!%login.country]]
<span class="error">[[+error.country]]</span>
</label>
<br />
<select name="country">[[!FormItCountryOptions? &selected=`[[!+fi.country]]`&prioritized=`US,GB,DE,RU,JP,FR,NL,CA,AU` &prioritizedGroupText=`Most registered` &allGroupText=`All countries`]]</select>
</p>
<p>
<label for="city">[[!%login.city]]
<span class="error">[[+error.city]]</span>
</label>
<br />
<input type="text" name="city" id="city" value="[[+city]]" />
</p>
<p>
<label for="website">[[!%login.website]]
<span class="error">[[+error.website]]</span>
</label>
<br />
<input type="text" name="website" id="website" value="[[+website]]" />
</p>
<p>
<label for="signature">Signature
<span class="error">[[!+up.error.signature:stripTags=`p,b,strong,i,a,ul,li`]]</span>
</label>
<br />
<textarea name="signature:allowTags" id="signature">[[!+up.signature]] cols="30" rows="10"</textarea>
</p>
<p>
<label for="use_display_name">Use Display Name in Forums
<span class="error">[[!+up.error.use_display_name]]</span>
</label>
<br />
<input type="hidden" name="use_display_name" id="use_display_name_hidden" value="0" /><input type="checkbox" name="use_display_name" id="use_display_name" value="1" [[!+up.use_display_name:FormItIsChecked=`1`]] />
</p>
<p>
<label for="display_name">Display Name
<span class="error">[[!+up.error.display_name]]</span>
</label>
<br />
<input type="text" name="display_name" id="display_name" value="[[+up.display_name]]" />
</p>
<p>
<label for="show_online">Show Online Status
<span class="error">[[!+up.error.show_online]]</span>
</label>
<br />
<input type="hidden" name="show_online" id="show_online_hidden" value="0" /><input type="checkbox" name="show_online" id="show_online" value="1" [[!+up.show_online:FormItIsChecked=`1`]] />
</p>
<p>
<label for="show_email">Show Email in Forums
<span class="error">[[!+up.error.show_email]]</span>
</label>
<br />
<input type="hidden" name="show_email" id="show_email_hidden" value="0" /><input type="checkbox" name="show_email" id="show_email" value="1" [[!+up.show_email:FormItIsChecked=`1`]] />
</p>
<p>
<div class="label"><img src="[[+Profile_Photos:phpthumbof=`w=120&h=120&zc=1&fltr[]=ric|20|20`]]" /></div> <span class="error">[[+fi.error.Profile_Photos]]</span>
<div class="input"><input id="Profile_Photos" name="Profile_Photos" type="file" value="[[+fi.Profile_Photos]]" maxlength="100000" /></div>
</p>
<br class="clear" />
<div class="form-buttons">
<br />
<p>
<input type="submit" name="login-updprof-btn" value="Update Profile" />
<span class="return-to-members-home"> return to <a href="[[~21]]">Members Home Page</a></span>
</p>
</div>
</form>
</div>
</div>
In line 111 and 112 is the avatar upload bit. I've also tried by replacing "Profile_Photos" with "avatarUpload". When I click the button, I can choose a file, and when "Update Profile" is clicked, I get no error message, but also don't get a saved message which I used to get.