can't find file to patch at input line nnn. File to patch:
No file to patch. Skipping patch. n out of n hunks ignored.

First make sure that you used the right patch command line, as shown above. If that still did not work, try with a higher n in -pn, up until maybe 6. To try without actually applying the patch, add --dry-run to the command line. With this option the patch is not actually applied but you get all the messages as if the patch were really applied. This allows you to determine whether there would be any errors, without having to the files from backup every time.

When you no longer get the error messages about not finding the file to patch, then you have found the right number for -p and you can repeat the command without --dry-run to actually apply the patch.

Hunk #n FAILED at nnn. n out of n hunks FAILED - saving rejects to file file.rej

This means that one or more changes, called hunks, could not be introduced into the file. Occasionally this could be because the patch was emailed or copied into a file and whitespace was either added or removed. Try adding --ignore-whitespace to the command line to work around this.

If you still get errors, it is most likely the patchfile was created for a version of eCosPro that is substantially different from the version you are using. In this event, please report this issue on the eCosCentric Bugzilla website.

Hunk #n succeeded at nnn (offset n lines) and
Hunk #n succeeded at nnn with fuzz n.

Usually there is no problem here and the patch could be applied completely. This message usually means that the patchfile was originally created for a slightly different version of eCosPro from the one you are using.

On rare occassions patch may think it applied the changes correctly but really did not. If something does not work and you think that the patch may have been applied incorrectly, please report this issue on the eCosCentric Bugzilla website.

malformed patch at line nnn

This message means that the patchfile is damaged. If you copy-pasted the patch from somewhere, be careful not to modify or damage it. A patchfile contains spaces at the start of lines and these often get lost in copy-paste. The safest mechanism is to download the patchfile and save it somewhere locally. If the browser does not download the patchfile and displays it instead, use File -> Save to save a copy locally.

Reversed (or previously applied) patch detected! Skipping patch.
Reversed (or previously applied) patch detected! Assume -R? [n]

This message usually means that a change in the patch is already contained in the file. The most common reason for this is that the version of eCosPro you are using already contains that patch or the patch was already applied. In this event do not apply the patch.