Any ideas what would cause this error?
What were you doing before this error occurred?
Adding, I have seen this error before. Although in multiple cases doing different things. None of them were repeatable as it was while manipulating a file, opening a file, blah blah blah. Each time it occurred there was no change to any of the files upon reopening or ignoring the error.
Not to say that this is what is happened(ing) with yours.
seems like a SW corrupted file ?
Possibly if you are working in older files there are some surfaces in older versions that are not readable now. I cannot remember off the top of my head what it was the last time I saw something like that. I think it was called "realview" graphic. It was on a pre 2007 model and the parts were transparent.
Like I said I am not sure if that is the situation you are seeing, but I have seen that error before.
But as I said only on older models which had things in them no longer supported by Solidworks.
Generally unexpected file format errors are caused by file corruption. Best thing to do is contact your SolidWorks re seller, they will probably ask you to send them the files via Pack and Go. They can analyse the files and perhaps send them to SolidWorks to attempt a repair. Not guaranteed though.
I second this answer
I had a similar problem once and I just restarted the whole computer and it worked, maybe you should try it too
Seen this before. Are all the part file updated to the release you are running. Try opening any sub-assemblies up first then open the final assembly.
I have encountered that before. It is a Solidworks file that has been corrupted, often due to a system crashing. I have sent the files to a VAR, and they let me know I was SOL. (BTW...Pack&Go only works on Solidworks files that Solidworks can actually open.)
Sometimes...I have been able to open the files simply by rebooting my system, launching Solidworks, and trying to open the files again. If the problem is occurring when you open an assembly, open and save each part file first...then with all the part files open, open any sub-assemblies...continue to work your way up until you are opening the main assembly but already have opened and saved everything the assembly references and all those files are already open in Solidworks. Doing this has worked for me a couple times.
I have corrected this the same way Doug Seibel has done it. If the re-boot / re-start doesn't work, find out what file(s) is causing the problem - only difference I would suggest is the divide and conquer method - close the assembly and then open each sub assembly one at a time until you find one or more that give the error. keep working down the line until you find the individual files or sub assemblies. Then try to open and fix and save them or see if you have a backup copy of that file that works.
Then work you way back up, opening the sub assemblies with the corrected file ...
With luck, you will only have one of two files to fix or update from backups if the open/ save / close doesn't correct the bad file.
Are all the files in that assembly native SW files or are some imported or from other systems.
Sometimes they will not translate correctly.
we keep guessing and provide answer to unknown question from Wayne - what file format he tried to open on SW and got error?
Retrieving data ...