"An error was encountered while trying to open your file. Contact Technical Support for a possible solution".

Chances are the file is corrupt, or the file has almost no size because it is a ~temp file.

Depending on what version of SolidWorks saved the file, you may be able to view its raw data in a viewer/editor like notepad++ or ViewAnything. Often you'll find the header is corrupted.

It is unlikely that the file can be repaired. Maybe someone at solidworks could try to repair the file, but it seems unlikely.

As a security measure, I sometimes corrupted the file header on purpose. Changing a single character is enough to result in an error message when opening the file. Without me, that file is no good, but it only takes a moment to "repair" if you knew what was changed.

I have seen this error a few times over the years.

Select the Assembly required to be Opened. Look for the Configuration box, select and change Default to Advance and then select Open. This will open a new window dialogue box – Configure Document

Select New configuration showing Assembly structure only. This will create a new configuration. Name the configuration something that is easily recognizable and select OK

The Assembly will now Open. All parts and sub-assemblies will be Suppressed. It is then just a case of Unsuppressing each of the individual parts or sub-assemblies one at a time.

even after this if it is not opening you have AMC support you can ask them else contact technical person from particular software and they might help you solving this.

or else your file may be corrupted.