Subversion downgrade and permission errors

We had a double-disk failure on RAID5 array last week (yes, it does happen). One of things that got affected was our source code repository.

So, we reinstalled etch and installed subversion, did svnadmin verify on repository and all seemed well until we tried to commit using SVN DAV. Apache's error log was full of errors like this:

Could not create activity /svn/repo/!svn/act/9526cf2d-4893-4b35-a843-4c0f2d9f8bc6. [500, #0]
could not open dbm files. [500, #120022]
Can't open activity db: APR does not understand this error code [500, #120022]

But, permissions where correct! In utter desperation, I even tried chmod 777 on repository (kids, don't try this at home!) but it didn't help.

What did help was:

svnadmin create
svnadmin dump repo | svnadmin load
mv repo repo.old
mv repo

Checking created repository with diff showed that it was indeed changed:

Binary files repo.old/dav/activities and repo/dav/activities differ
diff -rw repo.old/db/current repo/db/current
< 59 r9 1
> 62 ra 1
Only in repo/db/revprops: 60
Only in repo/db/revprops: 61
Only in repo/db/revprops: 62
diff -rw repo.old/db/revs/10 repo/db/revs/10
< id: aq.0.r10/17
> id: e1.0.r10/17
< pred: aq.0.r8/1443323
> pred: e1.0.r8/1443490
< dir b0.0.r8/1443476
> dir av.0.r8/1443643

and so on, for pages and pages.

I don't feel very good about changes, but repository was created with newer version from backports, and this time we used version from etch (thus downgrading from 1.4.6 to 1.4.2).

The whole point of this post is to help some random Google user with downgrade of subversion. So, here you have it!