JSF ajax requests causing a page refresh on specific browser - ajax

Question

I have a web application developed with Java 7, PrimeFaces 5 (JSF), Tomcat 7. Some time ago a user reported a defect from production environment where everything he clicked caused the page to be refreshed. I couldn't reproduce it then I forgot about it... but right now I just reproduced the issue, for the first time, running the application in my local machine. Any button I click, that triggers an ajax request, will be followed by a page refresh. I tried to restart tomcat and to clear Chrome's cache with CMD+SHIFT+R but I still can reproduce the issue.
I can reproduce on Google Chrome, but not on Firefox and Safari. I opened the network tab from Developer Tools from both Firefox and Chrome to compare the requests... but I still can't understand... does anybody have any idea what may be happening?
I will provide below the network activities for the following close event:
<p:panel id="myPanel" widgetVar="myPanelVar" closable="true">
<p:ajax event="close" listener="#{myBean.changeSomeVariables}" />
<h:outputText value="Example panel"/>
<a onclick="PF('myPanelVar').close();"><span class="ui-icon ui-icon-closethick"></span></a>
</p:panel>
Network activity from Firefox (working fine):
Request URL:http://localhost:8080/myMainPage;jsessionid=3BF25F4A5CF149326D3561C0F2002FB9
Request Method:POST
Status Code:200 OK
Remote Address:[::1]:8080
REQUEST HEADERS:
Host: localhost:8080
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:48.0) Gecko/20100101 Firefox/48.0
Accept: application/xml, text/xml, */*; q=0.01
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Faces-Request: partial/ajax
X-Requested-With: XMLHttpRequest
Referer: http://localhost:8080/myMainPage
Content-Length: 309
Connection: keep-alive
RESPONSE HEADERS:
Cache-Control: no-cache, no-store, must-revalidate, no-cache
Content-Length: 335
Content-Type: text/xml;charset=UTF-8
Date: Sun, 21 Aug 2016 03:02:14 GMT
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Pragma: no-cache
Server: Apache-Coyote/1.1
FORM DATA:
javax.faces.partial.ajax=true&javax.faces.source=myPanel&javax.faces.partial.execute=myPanel&javax.faces.behavior.event=close&javax.faces.partial.event=close&myHeaderForm=myHeaderForm&myHeaderForm%3Aemail=userTest&myHeaderForm%3Apassword=passTest&javax.faces.ViewState=3276447570579140768:319272761245257759
Network activity from Chrome (not working fine, I don't understand where the GET request is coming from):
Request URL:http://localhost:8080/myMainPage
Request Method:POST
Status Code:200 OK
Remote Address:[::1]:8080
REQUEST HEADERS:
POST /myMainPage HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Content-Length: 325
Origin: http://localhost:8080
Faces-Request: partial/ajax
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Accept: application/xml, text/xml, */*; q=0.01
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36
Referer: http://localhost:8080/myMainPage
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.8,pt;q=0.6
Cookie: JSESSIONID=5C1AE4DB6B1B5148BD81FD0E47002EA4
RESPONSE HEADERS:
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Set-Cookie: JSESSIONID=B68E094F6CF3C5AD57D96F0D1823AEBD; Domain=.mySite.com; Path=/; HttpOnly
Cache-Control: no-cache
Content-Type: text/xml;charset=UTF-8
Content-Length: 76
Date: Sun, 21 Aug 2016 03:05:36 GMT
FORM DATA:
javax.faces.partial.ajax=true&javax.faces.source=myPanel&javax.faces.partial.execute=myPanel&javax.faces.behavior.event=close&javax.faces.partial.event=close&myHeaderForm=myHeaderForm&myHeaderForm%3Aemail=userTest&myHeaderForm%3Apassword=passTest&javax.faces.ViewState=8492705007558548241%3A8154221161100277529
__________________________________________________________
Request URL:http://localhost:8080/myMainPage
Request Method:GET
Status Code:200 OK
Remote Address:[::1]:8080
REQUEST HEADERS:
GET /myMainPage HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Referer: http://localhost:8080/myMainPage
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8,pt;q=0.6
Cookie: JSESSIONID=5C1AE4DB6B1B5148BD81FD0E47002EA4
RESPONSE HEADERS:
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Set-Cookie: JSESSIONID=D352B9B5644288F3095D1A702075AFEB; Domain=.mySite.com; Path=/; HttpOnly
Content-Type: text/html;charset=UTF-8
Transfer-Encoding: chunked
Content-Encoding: gzip
Vary: Accept-Encoding
Date: Sun, 21 Aug 2016 03:05:36 GMT
Thanks