Compiler Warning (level 1) CS1687
Error MessageSource file has exceeded the limit of 16,707,565 lines representable in the PDB, debug information will be incorrect
The PDB and debugger have some limitations about how big a file can be. If the source file is too big, the debugger will not behave properly beyond that limit. The user should either not emit debug information for that file by possibly using #line hidden, or they should find a way to shrink the file, possibly by splitting the file into multiple files. They might want to use the partial keyword to split up a large class.