Updating engine w/ C++ (ERRORS)

[Travis.D]

I wanted to update from 4.24 to 4.26 so I:

1. Created a new blank C++ project in 4.26
2. Opened old project and migrated old Content to new Content
3. Copied CPP and H files from old Source to new Source
4. Updated H files line **class ProjOld_API AMyActor : public AActor **to class ProjNew_API AMyActor : public AActor
5. Rebuilt project (no errors or warnings)

But when I load the persistent level, a bunch of blueprints are missing (but not all) and I get a whole heap of errors (see pic).

Any ideas? Thanks in advance.

[Travis.D]

Okay, got there in the end.

I followed this guide:

https://nerivec.github.io/old-ue4-wiki/pages/migrate-content-between-projects.html#Migrating_from_C.2B.2B_Project_to_C.2B.2B_Project

Migrating from C++ Project to C++ Project

If you are migrating content from a C++ project to another C++ project, you will not have any custom items such as functions and variables that were compiled in the C++. For that you will need to use Visual Studio and copy/paste the corresponding C++ code from one project to the other, rename things, build the project binaries, and add core redirects to the project’s DefaultEngine.ini.
As specified in this helpful post:

• Copy/Rename

• Copy the OldProjectName’s source files to NewProjectName/Source/NewProjectName

• Autoreplace in whole project OldProjectName to NewProjectName

• Autoreplace in whole project OLDPROJECTNAME_API to NEWPROJECTNAME_API

• Rename OldProjectName.Target.cs

• Rename OldProjectNameEditor.Target.cs

• Rename OldProjectName.Build.cs

• Rename OldProjectName.[cpp,h]

• Add Core Redirects in NewProjectName/Config/DefaultEngine.ini (this is so the migrated content that uses C++ classes can find the new project’s classes):

[CoreRedirects] +ClassRedirects=(MatchSubstring=True,OldName=“/OldProjectName”,NewName=“/NewProjectName”) +EnumRedirects=(MatchSubstring=True,OldName=“/OldProjectName”,NewName=“/NewProjectName”) +FunctionRedirects=(MatchSubstring=True,OldName=“/OldProjectName”,NewName=“/NewProjectName”) +StructRedirects=(MatchSubstring=True,OldName=“/OldProjectName”,NewName=“/NewProjectName”)
Finally, after the newly migrated assets and maps are opened in the new project, there may be errors/warnings for the copied C++ classes. A resave of those assets will clear those errors.

But the formatting of the redirects is different. My version:

[CoreRedirects]
+ClassRedirects=(MatchSubstring=True,OldName="/Script/TF2020",NewName="/Script/TF2021")
+EnumRedirects=(MatchSubstring=True,OldName="/Script/TF2020",NewName="/Script/TF2021")
+FunctionRedirects=(MatchSubstring=True,OldName="/Script/TF2020",NewName="/Script/TF2021")
+StructRedirects=(MatchSubstring=True,OldName="/Script/TF2020",NewName="/Script/TF2021")
+PackageRedirects=(OldName="/Script/TF2020",NewName="/Script/TF2021")