Possibly a bit late but if you're frantically Googling this problem and your Subversion server has recently updated to Debian Buster you may want to try your luck with this option in your Apache's Subversion repository vhost:
SVNAllowBulkUpdates prefer
Put that after the SVNParentPath
directive, do sudo service apache2 reload
, and try a checkout again.
Source: https://audeuro.com/node/44
What this setting does (quoting from the subversion manual):
Toggles support for all-inclusive responses to update-style REPORT
requests. Subversion clients use REPORT requests to get information
about directory tree checkouts and updates from mod_dav_svn. They can
ask the server to send that information in one of two ways: with the
entirety of the tree's information in one massive response, or with a
skelta (a skeletal representation of a tree delta) which contains just
enough information for the client to know what additional data to
request from the server. When this directive is included with a value
of Off, mod_dav_svn will only ever respond to these REPORT requests
with skelta responses, regardless of the type of responses requested
by the client.
Most folks won't need to use this directive at all. It primarily
exists for administrators who wish—for security or auditing reasons—to
force Subversion clients to fetch individually all the files and
directories needed for updates and checkouts, thus leaving an audit
trail of GET and PROPFIND requests in Apache's logs. The default value
of this directive is On.
This sounds a bit out of date. I suspect that if you have a fairly large repository the size of an all-inclusive report may simply be too large for transit, so the "most folks won't need to use this directive at all" comment no longer applies.