Remove : from allowed client_secret chars (#8101)

Closes: https://github.com/matrix-org/synapse/issues/6766

Equivalent Sydent PR: https://github.com/matrix-org/sydent/pull/309

I believe it's now time to remove the extra allowed `:` from `client_secret` parameters.

1 files changed, 14 insertions, 0 deletions

diff --git a/CHANGES.md b/CHANGES.md

index d4cc179489..c1b8673c04 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,17 @@
+For the next release
+====================
+
+Removal warning
+---------------
+
+Some older clients used a
+[disallowed character](https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-register-email-requesttoken)
+(`:`) in the `client_secret` parameter of various endpoints. The incorrect
+behaviour was allowed for backwards compatibility, but is now being removed
+from Synapse as most users have updated their client. Further context can be
+found at [\#6766](https://github.com/matrix-org/synapse/issues/6766).
+
+
 Synapse 1.19.0 (2020-08-17)
 ===========================