Google cached multiple canonical formats but also "changetaxtype" and "changelanguage" SEO problem

Hi

We have get more than 1.000.000 cached page in the "google search console"
We have about 2300 URL in the sitemap

Our domain is https://www.elsag.dk (Version 4.0 migrated from 3.90 d. 11.03.2018 )
with nop-template themes and plugins.

Some is like this, (cached by google from the nopcommerce version 3.80 or 3.90)
I give the URL following number (our domain is tagged out "*"):
1)
*/changetaxtype/0?returnurl=/cee-vaegudtag-16a-230v-400v-ip44
2)
*/changelanguage/1?returnurl=/elektromotor-230v400v-50hz-ip55-1425-rpm-11kw-15hk-b3-fodmotor-3-faset-ie2
3)
*/changelanguage/1?returnurl=/elmotor-b5%3Fspecs%3D51%2C99%2C144%2C28
4)
*/elmotor-b14?specs=19,22,57,61&viewmode=grid

1)
If I check this with (no redirect rule in the "web.config") with following tool:
http://www.redirect-checker.org/index.php
I get Status code 302 (found) and 200 (as OK)
The ULR is redirected by nopcommerce to the correct URL:
/cee-vaegudtag-16a-230v-400v-ip44
I think the Status code "301" (redirect permanent) would be better?
We have had very bad experience with a´ redirect tool that used "302" -> "301" -> "200"
The problem is that google will not stop crawling the "URL" with "302" response.

2)
I have made rewrite rules "301" in the webconfig.
Did somebody have experience with permanent 301 redirect "canonical page" ?
If I make a´ google search for that theme i get different "best way"
Somebody says "Redirect", somebody "disallow robots" somebody "NoIndex/Follow tag"
and sure the "canonical" but I don´t think that the canonical work because the /changelanguage/ is slashed.

3)
Is like URL 2) but also with filter "specs"

4)
Nopcommerce return with filtered category page and view in grid.
When I check with the http://www.redirect-checker.org/index.php the page is found "200"
When I check with "canonical tool : http://www.seoreviewtools.com/canonical-url-location-checker/
It seems as the canonical tag work fine in the version 4.00
So, I think google just need some time to find out that it is a´ canonical page.

It would be great if there are other nopcommerce user that have experience with the same issue :)

Best Regards

Jens Ove Andersen

Hi again,

I have tried following in the nopcommerce demo store:

standard URL:
http://demo.nopcommerce.com/camera-photo

When I insert "changelanguage/1?returnurl=/" as below.

http://demo.nopcommerce.com/changelanguage/1?returnurl=/camera-photo
At the first view it seems like evrything OK. The typed URL redirect to the correct:
http://demo.nopcommerce.com/camera-photo

But when I check the URL:
http://demo.nopcommerce.com/changelanguage/1?returnurl=/camera-photo
with
http://www.redirect-checker.org/index.php
I see that the page is redirected with HTTP response status code "302" Found.

That means that have "google-bot" cached the:
http://demo.nopcommerce.com/changelanguage/1?returnurl=/camera-photo

and get status code "302" found it will keep looking for that URL.

I get the same result if I try it with "changetaxtype" as following:
http://demo.nopcommerce.com/changetaxtype/0?returnurl=/camera-photo

The main problem is that Google bot "spider" have cached at lot of page with this and
combined it with "specs" and viewmode and other tax type "Number"  and language "Number"

I don´t know why this come ?

When I make following search in google:
changetaxtype site:dk

I can see in the result "URL" that other store owner have the same problem.

I have also tried at our online page to shift between vat included / vat excluded.
After that I checked the logfiles at our server and I see that I get following string:

2018-03-20 15:29:03 195.201.13.108 GET /changetaxtype/0?returnurl=/schukostik-med-jord-ip44-230v "HTML code 302"
2018-03-20 15:29:03 195.201.13.108 GET /schukostik-med-jord-ip44-230v "HTML code 200"

First 302 and then 200

And when I change the tax setting again:
2018-03-20 15:29:03 195.201.13.108 GET /changetaxtype/10?returnurl=/schukostik-med-jord-ip44-230v "HTML code 302"
2018-03-20 15:29:03 195.201.13.108 GET /schukostik-med-jord-ip44-230v "HTML code 200"

I hope the problem is understandable.
It's a little hard to describe :-)


Best Regards

Jens Ove

PS:
When I online "Front" change the Incl/Excl. Tax
The page code is changed but the same redirect "URL".
Is this not a´ SEO problem ?