diff --git a/src/components/views/rooms/MessageComposer.js b/src/components/views/rooms/MessageComposer.js
index 2fc35d80cc..f7a67c2189 100644
--- a/src/components/views/rooms/MessageComposer.js
+++ b/src/components/views/rooms/MessageComposer.js
@@ -349,6 +349,34 @@ export default class MessageComposer extends React.Component {
         const canSendMessages = !this.state.tombstone &&
             this.props.room.maySendMessage();
 
+        // TODO: Remove temporary logging for riot-web#7838
+        // Note: we rip apart the power level event ourselves because we don't want to
+        // log too much data about it - just the bits we care about. Many of the variables
+        // logged here are to help figure out where in the stack the 'cannot post in room'
+        // warning is coming from. This means logging various numbers from the PL event to
+        // verify RoomState._maySendEventOfType is doing the right thing.
+        const room = this.props.room;
+        const plEvent = room.currentState.getStateEvents('m.room.power_levels', '');
+        let plEventString = "<no power level event>";
+        if (plEvent) {
+            const content = plEvent.getContent();
+            if (!content) {
+                plEventString = "<no event content>";
+            } else {
+                const stringifyFalsey = (v) => v === null ? '<null>' : (v === undefined ? '<undefined>' : v);
+                const actualUserPl = stringifyFalsey(content.users ? content.users[room.myUserId] : "<no users in content>");
+                const usersPl = stringifyFalsey(content.users_default);
+                const actualEventPl = stringifyFalsey(content.events ? content.events['m.room.message'] : "<no events in content>");
+                const eventPl = stringifyFalsey(content.events_default);
+                plEventString = `actualUserPl=${actualUserPl} defaultUserPl=${usersPl} actualEventPl=${actualEventPl} defaultEventPl=${eventPl}`;
+            }
+        }
+        console.log(
+            `[riot-web#7838] renderComposer() hasTombstone=${!!this.state.tombstone} maySendMessage=${room.maySendMessage()}` +
+            ` myMembership=${room.getMyMembership()} maySendEvent=${room.currentState.maySendEvent('m.room.message', room.myUserId)}` +
+            ` myUserId=${room.myUserId} roomId=${room.roomId} hasPlEvent=${!!plEvent} powerLevels='${plEventString}'`
+        );
+
         if (canSendMessages) {
             // This also currently includes the call buttons. Really we should
             // check separately for whether we can call, but this is slightly
@@ -425,6 +453,8 @@ export default class MessageComposer extends React.Component {
                 </div>
             </div>);
         } else {
+            // TODO: Remove temporary logging for riot-web#7838
+            console.log("[riot-web#7838] Falling back to showing cannot post in room error");
             controls.push(
                 <div key="controls_error" className="mx_MessageComposer_noperm_error">
                     { _t('You do not have permission to post to this room') }