Quartus internal error (an old Quartus version)

[Altera_Forum]

Dear all, 

 I have been using an old Quartus version like 8.0 for some reason.   When I modify and compile a design, I am seeing the following error very often when Quartus is generating assembler (generating .sof file). The modification was simple like renaming bus using wire component (I am using schematic environment.)  Does anyone have any experience or reason for this? --------------------------------- Internal Error: Sub-system: CUT, File: /quartus/db/cut/cut_lcell_util.cpp, Line: 6687 Error in merging. Locked bit differs Stack Trace: 0x2AE31A : CUT_LCELL_UTIL::debug_output + 0x174A (db_cut)   End-trace  Quartus II Version 8.0 Build 215 05/29/2008 SJ Full Version -------------------------------- I am attaching the screen capture as well.  Thanks.

[Altera_Forum]

try deleting the db and incremental_db directories from the synthesis directory and see if it completes that way.. 

 It sounds like it's an issue merging the database,,

[Altera_Forum]

Hi,  

 I get this problem too. How to solve it?..Where to find the db and incremental_db..need helps

[Altera_Forum]

in the project directory. simply delete them to try the suggested work around

[Altera_Forum]

Did you mean delete them from the project folder? thanks for reply

[Altera_Forum]

--- Quote Start ---  try deleting the db and incremental_db directories from the synthesis directory and see if it completes that way..  It sounds like it's an issue merging the database,,  --- Quote End ---    Still having the same problem. Do you have any other suggestion, please?  Thanks!

[Altera_Forum]

I have the same problem with Quartus 11.0SP1. I deleted the complete project folder, but still get the same problem. 

Any solution?

[Altera_Forum]

Unfortunately, no perfect solution yet. 

I just recovered the design from a backup file and carefully modified from there.