@rhellyer Could you test my PR that should resolve your problem:

Changes you can see at:
https://github.com/joomla/joomla-cms/pull/11343/files

Download file from https://raw.githubusercontent.com/csthomas/joomla-cms/10e721c4a93d568d581ea4296c7bf07043482c6b/libraries/cms/router/site.php

and copy it to /libraries/cms/router/site.php

Then test you request as you mentioned at #6488 (comment)

Thanks for the description.

I've tried it again with the new /libraries/cms/router/site.php file and it is still throwing that error
This is the error_log where the last two entries are after I made the change to the new file.

[28-Jul-2016 02:58:13 America/Denver] PHP Notice: Undefined index: view in /home2/danclend/public_html/components/com_content/router.php on line 73
[28-Jul-2016 04:25:39 America/Denver] PHP Notice: Undefined index: view in /home2/danclend/public_html/components/com_content/router.php on line 73
[28-Jul-2016 05:03:24 America/Denver] PHP Notice: Undefined index: view in /home2/danclend/public_html/components/com_content/router.php on line 73
[28-Jul-2016 14:03:01 America/Denver] PHP Notice: Undefined index: view in /home2/danclend/public_html/components/com_content/router.php on line 73
[28-Jul-2016 14:05:51 America/Denver] PHP Notice: Undefined index: view in /home2/danclend/public_html/components/com_content/router.php on line 73


I did double check that the new site file contained the two latest code changes that you had made.
I'll see if I can replicate the error on our dev version of the site, because that way I would be able to test other changes.
Richard

I was able to replicate the issue with the dev version of our website. and these are the errors before and after installing the patched version of site.php

BEFORE

AFTER

I'm sorry but this PR not resolve your problem.

You have back to #6488.
I will write instruction again on #6488.

@csthomas has this PR to be tested or #6488?

Yes. I rebased PR to be simpler patch joomla and updates test instruction.

I have tested this item ✅ successfully on d22a66d

Had set an Menue-Alias (id:107) to an existing Menue (Category-Blog). With Patch the index.php?Itemid=107 shows Menue correct, without Patch got 404-Errorpage.

Thanks for test

@csthomas There is another minor problem that should fixed. When you edit the alias menu item in backend, you will see that the read-only Link field contains "index.php?Itemid=" when it should contain "index.php?Itemid=".

Probably but it should be fixed in separate PR.

For now this PR stay here 6 month and have not yet 2 success tests (only one).
If you tested it successful then you can mark test as success and this PR could be merged to joomla.

You can mark your test at:
https://issues.joomla.org/tracker/joomla-cms/11343

Please login and then go to above URL, click "Test this", check option and submit test result.
After 2 success tests it may go forward.

I have tested this item ✅ successfully on d22a66d

Done !

Thanks

When you edit the alias menu item in backend, you will see that the read-only Link field contains "index.php?Itemid=" when it should contain "index.php?Itemid=XXXX".

You can create your own issue about it.
That way more contributors will know about the problem and may add fix.
Off course you also can fix it by creating your own PR.

RTC