Today I upgraded some reports from SSDT 2010 to 2015. Most of them seem to be OK although the one that I most want to work on has developed problem. When I switch to the Preview Pane I get the errors message "An error has occurred during local report processing".
The report worked immediately after importing but started to produce this error after some simple changes where made. Thinking the obvious, I deleted the project and replaced it with a fresh copy of the SSDT 2010 version, but now I get this error before any changes are made. The report continues perfectly well in SSDT 2010, and when deployed to a Report server.
Compared to the other reports in the project this report has a lot more columns (about 50) and is the only one based on the List object, the others are Table or Matrix reports, I try to stay away from List. It is basically a pretty simple report though.
There are no errors and just a few warnings, some to with overlapping objects and one that says "Custom parameter layout was removed from the report. SQL Server 2014 Reporting Services and earlier do not support custom parameter layout." which refers to another report.
Any suggestions on what to do would be much appreciated.
EIDIT. On the off chance, I tried something that worked. I created a new project, copied the report RDL file to it and added it to the new project. Now it works. I can only think that some corrupted information about the report was caches somewhere outside the report project folders which survived even after I deleted the original report folder and copies in a fresh one.
R Campbell