After a DIW install to replace a single form on a DE 6.53 application the following error occurs preventing application access.

Error 1 Opening Application
Operation Failed

Any ideas on how to resolve this?

Error 1 is problem with opening a file.

So either missing, corrupted, locked or wrong name.

sorted.
restarted server.

Should always be the goto place for peculiar problems... ;-)

I know a lot of people are loath to do it as so much other stuff is on/using the same server but the sad truth is that a server restart on a regular basis will iron out a lot of peculiar problems. No software is without fault - bar DFD 4.53 ;-) and Novell 3.11 (We had a server that ran for almost 6 years without a restart and then we had to upgrade the memory.... it was a hard but necessary duty to switch it off to get the job done).

We had one customer that had problems for 2 weeks and we suggested everything, he sent samples to us - they all worked - but nothing work. The only advice he didn't listen to (and we had assumed he had) was to restart the server (it came out that so many systems used it and so many users that he wouldn't do it) after two weeks we asked him straight out if he had restarted the server and he admitted he hadn't. 

Obviously when he finally found the "Swedish switch" it was all honkey dory.