The mysterious occurrence of "Undefined" popping up in the URL of my ASP.NET application, could this be somehow linked to Google?

Question

The mysterious occurrence of "Undefined" popping up in the URL of my ASP.NET application, could this be somehow linked to Google?

Several users are encountering a perplexing issue while using my web application.

During their usage, they click on a button or link that redirects them to another page, but encounter a "page not found" error with a URL like:

undefined

I initially suspected a javascript bug in my app: a redirect triggered by selecting a page name (potentially with parameters) where one value is incorrect, resulting in the page name being set to "undefined". However, there is no such code present in my app, and this problem occurs on various pages at random.

It appears to occur more frequently when users initially log in by clicking a link in a Gmail email message. Yet, a user who manually entered the link into a browser window reported the same issue. Some online research hints at potential Google redirection or caching processes taking place behind the scenes.

Any insights?

Edit:
Seeking input from individuals knowledgeable about how Gmail links function; which SO tags attract Google experts?

Edit 2:
Offering a bounty for the top answer sharing helpful information and temporary workaround suggestions. Still open to discovering the actual resolution to the problem, hence not considering the workaround as a definitive solution.

javascript asp.net url undefined

Answer 1

Answer №1

It seems that Gmail may be altering the links in some way, as shown in the image below:

Non-standard header fields are typically identified by prefixing the field name with X-

It appears to be behaving similar to Google, inspecting all aspects of the content.

To prevent Google from tracking my clicks on searches, I had to develop a userscript to modify one of their functions:

rwt = function(){};

You could consider implementing a similar solution for Gmail.

What is rwt?

rwt() is a JavaScript function used by Google search to track visited sites through link redirection.

For instance, a search for "greasemonkey" displayed the Mozilla add-ons page as the top result. Upon clicking, it redirected from:

https://www.google.com.br/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCUQFjAA&url=https%3A%2F%2Faddons.mozilla.org%2Fpt-BR%2Ffirefox%2Faddon%2Fgreasemonkey%2F&ei=iWNtUIXjIoyQ8wTxv4DQAQ&usg=AFQjCNEO9EJcHp9rAmKyD_XZF2Bt6hs_YQ&sig2=P19xVUsD-Q1G_9AiUBP3PQ

to:

https://addons.mozilla.org/pt-BR/firefox/addon/greasemonkey/

The image above and the use of rwt() illustrate that Gmail may also be changing links, potentially connected to your issue.

As there may be limitations on Gmail's end, you could address this on your server by redirecting

http://www.correctwebsitename.com/undefined

to

http://www.correctwebsitename.com

, or any preferred page for user interaction.

To handle referrals from Gmail or other sources landing on

http://www.correctwebsitename.com/undefined

, ensure they are redirected appropriately.

Can I simply redirect them back to their initial page?

ASP

if not request.UrlReferrer is nothing then
    response.redirect (request.UrlReferrer.tostring)
end if

JS (note: creating a undefined page is necessary for this code snippet to work properly)

if (window.location.href.toLowerCase().indexOf('undefined') > -1) {
    window.location.href = document.referrer;
}

Keep in mind that direct URL entry or using favorites may not have a referrer set.

Answer 2

It seems that Gmail may be altering the links in some way, as shown in the image below:

Non-standard header fields are typically identified by prefixing the field name with X-

It appears to be behaving similar to Google, inspecting all aspects of the content.

To prevent Google from tracking my clicks on searches, I had to develop a userscript to modify one of their functions:

rwt = function(){};

You could consider implementing a similar solution for Gmail.

What is rwt?

rwt() is a JavaScript function used by Google search to track visited sites through link redirection.

For instance, a search for "greasemonkey" displayed the Mozilla add-ons page as the top result. Upon clicking, it redirected from:

https://www.google.com.br/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCUQFjAA&url=https%3A%2F%2Faddons.mozilla.org%2Fpt-BR%2Ffirefox%2Faddon%2Fgreasemonkey%2F&ei=iWNtUIXjIoyQ8wTxv4DQAQ&usg=AFQjCNEO9EJcHp9rAmKyD_XZF2Bt6hs_YQ&sig2=P19xVUsD-Q1G_9AiUBP3PQ

to:

https://addons.mozilla.org/pt-BR/firefox/addon/greasemonkey/

The image above and the use of rwt() illustrate that Gmail may also be changing links, potentially connected to your issue.

As there may be limitations on Gmail's end, you could address this on your server by redirecting

http://www.correctwebsitename.com/undefined

to

http://www.correctwebsitename.com

, or any preferred page for user interaction.

To handle referrals from Gmail or other sources landing on

http://www.correctwebsitename.com/undefined

, ensure they are redirected appropriately.

Can I simply redirect them back to their initial page?

ASP

if not request.UrlReferrer is nothing then
    response.redirect (request.UrlReferrer.tostring)
end if

JS (note: creating a undefined page is necessary for this code snippet to work properly)

if (window.location.href.toLowerCase().indexOf('undefined') > -1) {
    window.location.href = document.referrer;
}

Keep in mind that direct URL entry or using favorites may not have a referrer set.

Answer 3

Answer №2

It is recommended to review the following aspects within your application.

Is there any external code present in your application, aside from your own?

External applications can inject code, such as "AddThis" which sometimes adds an extra #parameter to your URL. In this case, it appears that a JavaScript function is manipulating the location.href as "undefined," a common issue for many JavaScript developers.

Adding a # can facilitate cross-site communication and may be contributing to the problem.

Perform a thorough search in your code for instances of "location.href" to identify where it is being used.

Sometimes browser extensions from third-party sources could also be causing the problem.

These suggestions should assist you in pinpointing the root cause of the issue.

If you are unable to identify the problem elsewhere, consider overriding the 404 functionality on your webserver and utilizing Referrer to implement a solution.

Answer 4