Subject page type N lock denied(216) or lock conversion denied(215)

Is bug fixed in FB 2.5.3?

We have had this bug in two FB 2.5.2 classic server installs and it still appears sometimes after updating to 2.5.3.

Page number in error message indicates that page belong to tables with moderate UPDATE load (30-60 updates per second, each record is updated in 10-30 seconds). All updates performed by one connection and updating transaction is committed and started anew each 15 seconds.

Rate of error had grown significally after deployment of new application server which uses JDBC (Jaybird) Firebird connection and constantly (each 10-15 seconds) executes SELECT queries, including above-mentioned tables.

Both servers use Windows x64 (2008 and 2012) and 32-bit FB builds (32-bit udfs are used, so we cannot switch to 64-bit FB for now).