Applies To:
  • CitectSCADA 5.10

This error will occur if Citect cannot successfully complete a PageDisplay() command. Citect will attempt to open the destination page .rdb file. If this fails, it will fall back to the current page. If the operating system prevents access to this file, the message "Cannot Open Page" will be displayed and Citect will shut down. This can occur if the Citect database is accessed over a network and the network link is lost. It can also happen if Citect runs out of file handles. Citect can open a maximum of 32K file handles. There is no way to tell how many file handles Citect has used. A repetitive function that only opens files and doesn't close them will leak file handles and Citect will eventually run out of this resource. 

If a network is suspected, try placing the database on a local drive. If the network has been eliminated, check all project Cicode for all uses of FileOpen() and DevOpen(). Check that there is a corresponding FileClose() or DevClose() to free up the file handle. Check the functions that are run numerous times first, e.g. from events, reports, or file access within loops.