A flat coextruded biaxially-oriented and thermoset barrier film, comprising, (i) at least one outer heat sealable layer, mainly made of a (co)polyolefin with a Vicat softening temperature not exceeding 130 °C, (ii) at least one heat resistant layer, mainly made of at least one polar (co)polymer selected from the group comprising predominantly aliphatic (co)polyamides and aromatic (co)polyesters, (iii) at least one core adhesive layer made of a material capable of adhering to both (co)polyolefins and polar (co)polymers, wherein a. said heat resistant layer, mainly consisting of predominantly aliphatic (co)polyamides, comprises not less than 15% of at least one predominantly aliphatic copolyamide with a melting temperature not above 205 °C; b. a shrinkage value of the film in each a machine and a transverse directions after immersion for 10 seconds in water at a temperature of 90 °C is less than 10%; c. a shrinkage value of the film in at least one of the machine and the transverse directions is less than 3% after dwelling for 10 seconds in a drying cabinet preheated to 100 °C; d. the film is thermoformed so that not less than 99% of the products thermoformed from the film are undamaged, and the ratio between a mean thickness in unstrained film areas and a mean minimum thickness of the film in a resulting formed product, measured as disclosed in the description, is not more than 4.5, when vacuum thermoforming is carried out automatically by a thermoforming machine at a preset temperature of 100 °C, a heating time of 3 s, a forming time of 2.5 s and a vacuum system pressure of 267 Pa (2 mm Hg), by means of a forming die with four molding cavities in the form of rectangular parallelepipeds, each with the overall dimensions of 147×143×50 mm and rounding edges with a radius of 20 mm, assembled in a rectangular block with 18 mm gaps between the molding cavities in the machine direction and 15 mm gaps in the transverse direction. (i) at least one outer heat sealable layer, mainly made of a (co)polyolefin with a Vicat softening temperature not exceeding 130 °C, (ii) at least one heat resistant layer, mainly made of at least one polar (co)polymer selected from the group comprising predominantly aliphatic (co)polyamides and aromatic (co)polyesters, (iii) at least one core adhesive layer made of a material capable of adhering to both (co)polyolefins and polar (co)polymers, a. said heat resistant layer, mainly consisting of predominantly aliphatic (co)polyamides, comprises not less than 15% of at least one predominantly aliphatic copolyamide with a melting temperature not above 205 °C; b. a shrinkage value of the film in each a machine and a transverse directions after immersion for 10 seconds in water at a temperature of 90 °C is less than 10%; c. a shrinkage value of the film in at least one of the machine and the transverse directions is less than 3% after dwelling for 10 seconds in a drying cabinet preheated to 100 °C; d. the film is thermoformed so that not less than 99% of the products thermoformed from the film are undamaged, and the ratio between a mean thickness in unstrained film areas and a mean minimum thickness of the film in a resulting formed product, measured as disclosed in the description, is not more than 4.5, when vacuum thermoforming is carried out automatically by a thermoforming machine at a preset temperature of 100 °C, a heating time of 3 s, a forming time of 2.5 s and a vacuum system pressure of 267 Pa (2 mm Hg), by means of a forming die with four molding cavities in the form of rectangular parallelepipeds, each with the overall dimensions of 147×143×50 mm and rounding edges with a radius of 20 mm, assembled in a rectangular block with 18 mm gaps between the molding cavities in the machine direction and 15 mm gaps in the transverse direction.