During the creation and processing of items (pressure vessels, heat exchangers) with NextGen, the program takes care of keeping some backup copies -- or backup -- useful in case of corruption of the file you are working on. This corruption can occur due to a power failure, an abnormal software shutdown, hardware damage.
The first backup copy is autosave: every 'n' minutes, the program creates an automatic backup. When a file is reopened, the program checks to see if there is a more recent automatic save and will eventually ask the user to restore it.
Parallel to this, whenever the user adds a component or makes a substantial change to the file he is working on, the program keeps a copy of the previous file. The number of copies retained is set by default to 5 but this value can be changed.
Both these settings can be changed via the Tools> Options> General menu in the "Program" section.
If there is a problem opening a file, you can try to recover one of the previous versions. The previous versions are stored in the same folder that contains the NextGen projects (by default Documents \ Sant'Ambrogio Projects ), in the "Backup" sub-folder. This sub-folder contains a tree similar to the one in "Sant'Ambrogio Projects". It is necessary to first identify the project folder, then the folder with the name of the item to be recovered. Generally, this folder contains an "Item ID.txt" file and one or more ".sit" files.
The file with "Autosave" in the name is the last available automatic save.
The other files, named "Item name (dd-mm-yyyy or: mm: ss) .sit" are backup copies of the date and time indicated in the file name (dd-mm-yyyy or: mm: ss) .
It is possible to try the recovery, once identified the file that you want to recover, through the "import" function of the Project Browser, explained in this article. It is advisable to start from the most recent file (again based on the date shown in the name) and proceed backwards. The files imported using the "import" function never overwrite those present: the program creates additional copies.
If it is not possible to recover a backup copy through this procedure, unfortunately the corrupt file is not to be considered recoverable. We recommend that you reduce the autosave time and perform more frequent manual saves, possibly increasing the number of copies to keep.
File corruptions are due to disk write errors due for example to sudden power or network failure or to temporary write errors. They should not happen regularly, if this happens then it is likely that the drive you are saving to has hardware problems that we recommend investigating.