Unknown error when upgrading from SSRS 2014 to 2016

Question

I had to upgrade the report server used by some application from SSRS 2014 to SSRS 2016.

I did the migration manually, because the old and new SSRS were installed on different machines, and I could not do an in-place update.

So the approach was (long story short):

• backup ReportServer on SSRS 2014
• install SSRS 2016 on new server
• restore ReportServer database
• update its structure to match SSRS 2016; I used Sql Compare to get structure from an in-purpose, empty ReportServer database created by SSRS 2016
• added record in ServerUpgradeHistory with version for SSRS 2016 (173)
• restored the Encryption keys from SSRS 2014.

Everything works ok, with one small issue.

When I try to open SSRS Web Portal URL (http://...myServer.../Reports), or to refresh main page, I get the following error popup.

This error doesn't appear to affect the functionality of SSRS - all reports work just fine. Also it does's appear when opening Web Service URL (http://...myServer.../ReportServer).

So it's just annoying so far.

I searched for the guid string in Catalog table (I thought it might be some folder name or something), but I found nothing.

Does anyone have any idea where it comes from and how to get rid of it?

Thank you

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Edit

Recently I updated from SSRS 2016 to 2017, and I kept carrying this error with me. However I found the offending item. It is in Catalog table, and it is of Type = 3 (Resource), with mime-type application/octet-stream

I deleted it from catalog (I did a backup of it into a separate table - catalog_bak), but I still get the error when I load main page in (/reports)

Beside that, it never pops-up again, with one exception: it always shows-up when I access Site Settings -> Branding

I guess it has something to do with branding packages. Does anyone knows where are they stored, and how can I uninstall / clean-up that?

Answer 1

For me Uninstall and Reinstall did the trick for me.

Answer 2

A Branding Package is created by a user. If the original package can't be found or is corrupted it should revert to the default. Have you tried removing the package or creating and uploading a new one? Also, try downloading SQL Server Mobile Report Publisher (https://www.microsoft.com/en-us/download/details.aspx?id=50400) and then connect your server with it. It may contain a theme that was used on your original server.