Can't save file as .psd

[LeeO2912]

Pls help! I can't save as psd. file because of the "save" or "save as" dialog box does not appear. When I clicked on "save" or "save as" nothing happen...that means I can only use "export", but I need to keep my process as psd. 

I  renamed it to ~UXP too, but it's doesn't help at all...

[Myra Ferguson]

See if this information helps:

Program error when opening or saving files

[Mohammad.Harb]

Whihc photoshop version are you using ? 
Update to the most recent version, if that doesn't work out, roll back to a previous version .