Sometimes reports stop working after uploading newer report definition (RDL) – but definition is 100% proper?
Example of error message:
The definition of this report is not valid or supported by this version of Reporting Services. The report definition may have been created with a later version of Reporting Services, or contain content that is not well-formed or not valid based on Reporting Services schemas. Details: '.', hexadecimal value 0x00, is an invalid character. Line 4632, position 10.
You have to check the end of report definition (eg. using notepad) and look for space character – deleting this “blank” characters solves problem!